AfterSales Training. Climate Control Systems Diagnosis & Repairs P80

Transcription

1 AfterSales Training Climate Control Systems Diagnosis & Repairs P80

2 Porsche AfterSales Training Student Name: Training Center Location: Instructor Name: Date: Electrical Troubleshooting Logic 1 - Do you understand how the electrical consumer is expected to operate? 2-Do you have the correct wiring diagram? 3-If the circuit contains a fuse, is the fuse okay & of the correct amperage? 4-Is there power provided to the circuit? Is the power source the correct voltage? 5-Is the ground(s) for the circuit connected? Is the connection tight & free of resistance? 6 - Is the circuit being correctly activated by a switch, relay, sensor, microswitch, etc.? 7-Are all electrical plugs connected securely with no tension, corrosion, or loose wires? Important Notice: Some of the contents of this AfterSales Training brochure was originally written by Porsche AG for its restof-world English speaking market. The electronic text and graphic files were then imported by Porsche Cars N.A, Inc. and edited for content. Some equipment and technical data listed in this publication may not be applicable for our market. Specifications are subject to change without notice. We have attempted to render the text within this publication to American English as best as we could. We reserve the right to make changes without notice Porsche Cars North America, Inc. All Rights Reserved. Reproduction or translation in whole or in part is not permitted without written authorization from publisher. AfterSales Training Publications Dr. Ing. h.c. F. Porsche AG is the owner of numerous trademarks, both registered and unregistered, including without limitation the Porsche Crest, Porsche, Boxster, Carrera, Cayenne, Cayman, Panamera, Tiptronic, VarioCam, PCM, 911, 4S, FOUR, UNCOMPROMISED. SM and the model numbers and distinctive shapes of Porsche's automobiles such as, the federally registered 911 and Boxster automobiles. The third party trademarks contained herein are the properties of their respective owners. Specifications, performance standards, options, and other elements shown are subject to change without notice. Some vehicles may be shown with non-u.s. equipment. Porsche recommends seat belt usage and observance of traffic laws at all times. Printed in the USA Part Number - PNA P Edition - 8/10

3 Table of Contents Chapter Description Section Introduction i A/C Refrigerant System Service and Diagnosis Air Conditioning Basics System Descriptions Boxster (986), Boxster/Cayman (987) & 911 (996/997) Cayenne (9PA) (E1 1st & 2nd Generations) Cayenne (92A) 2011 (E2) Cayenne S Hybrid (92A) 2011 (E2) Panamera (970) n Conversion Charts Climate Control Systems Diagnosis & Repair

4 Climate Control Systems Diagnosis & Repair

5 Introduction In the past, air conditioning in automobiles was considered an option and a luxury. A/C was rarely found in high performance vehicles and the customer was willing to trade comfort for performance. The rules have changed and today s customer expects A/C to be an included feature. High levels of performance and comfort are expected. All current Porsche models sold in North America have A/C standard. With the push of a button, today s customer expects rapid heating and cooling. Only when the system fails to function will the customer be consciously aware of it. This is where you, the technician, come in. In order to satisfy the Porsche customer s high expectations, you will need to successfully diagnose, test and repair climate control systems in a timely manner. After a climate control system repair, the first thing that the customer will do is operate the system. Success or failure is measured in degrees. Climate Control Systems Diagnosis & Repair Page i

6 Introduction Ozone Depletion and Global Warming The Ozone layer is in the stratosphere kilometers (10-30 miles) above the Earth's surface. This layer shields the earth from much of the sun's ultraviolet radiation. Chlorine found in R-12 refrigerant released into the atmosphere can seriously damage the Ozone layer. Energy from the sun drives the earth's weather and climate. Sunlight heats the earth's surface, and some of the sunlight is reflected in the form of infrared radiation. Much of this radiant energy dissipates into space, but some is reflected back into the atmosphere. Atmospheric greenhouse gases (water vapor, Carbon Dioxide, and other gases) trap some of the outgoing energy, retaining heat (like the glass panels of a greenhouse). The trapping of too much radiant heat energy is suspected to cause Global Warming. There is strong evidence that the quantity of Carbon Dioxide in the atmosphere and the rising average world temperatures are related. Carbon Dioxide, one of the gases emitted by internal combustion engines, has a significant greenhouse effect, but R-12 refrigerant in the upper atmosphere has a Global Warming Potential (GWP) 8,500 times greater than Carbon Dioxide. R-134a refrigerant is better, but still has a GWP value of 1,300. The discovery of these problems caused the governments of the industrialized world to establish a time table for the reduction and eventual elimination of the production of chemicals that deplete the Ozone layer. The Montreal Protocol was enacted in September 1987, and laws were enacted requiring the automotive service industry to modify the servicing of A/C refrigerant systems. All refrigerants used in automotive air conditioners must now be recovered and recycled whenever an A/C system is opened for service or repair. Also, refrigerant R-12 (FREON) is no longer produced, and has been replaced with a less harmful refrigerant, R-134a (SUVA). R-134a is the only alternative refrigerant for R-12 that is approved for use in new automobiles by all auto manufacturers. Porsche phased-in the use of R-134a in Refer to page I-21 for more refrigerant information. Any person servicing motor vehicle air conditioning systems MUST by law be properly trained, certified and use approved refrigerant recycling equipment. Technicians must successfully complete an EPA approved recycling course and be tested. Certification is available from the National Institute for Automotive Service Excellence (ASE) and the Mobile Air Conditioning Society (MACS). State and local jurisdictions may have their own certification requirements that supersede federal requirements. Page ii Climate Control Systems Diagnosis & Repair

7 A/C Refrigerant System Service & Diagnosis Subject Page A/C Refrigerant System Service Environmental Impact A/C Service Equipment Equipment Maintenance A/C Refrigerant System Service Procedures A/C System Performance Testing Warnings and Cautions Service Equipment Safety First Aid Climate Control Systems Diagnosis & Repair Page 1.1

8 A/C Refrigerant System Service & Diagnosis Notes: Page 1.2 Climate Control Systems Diagnosis & Repair

9 A/C Refrigerant System Service & Diagnosis A/C Refrigerant System Service Before 1992, automotive air conditioning services could be performed by anyone with a manifold gauge set, cans of refrigerant and a can tap. Refrigerant was inexpensive and considered harmless. Do-it-your-selfers routinely topoff leaking systems rather than paying for expensive repairs. In repair shops, refrigerant was routinely vented to the atmosphere whenever an A/C system needed to be opened. This was accepted practice. At the time, the environmental effects were unknown and methods to recover refrigerant were not available. R-12 was so inexpensive that its complete loss and replacement was seen as insignificant. A/C Service Equipment By law, all automotive repair facilities performing A/C system services must have approved equipment to recover and recycle refrigerant R-134a. If the shop also services vehicles with R-12 or any other refrigerant, it must have separate equipment for those refrigerants as well. All refrigerant recovery and recycling equipment must be certified to meet the Society of Automotive Engineers (SAE) standards for performance and refrigerant purity. Equipment Maintenance Environmental Impact Things changed when it was discovered that R-12 released into the atmosphere has contributed to two serious effects: destruction of Ozone in the stratosphere, and global warming. The Clean Air Act legislation of 1990 included these provisions: A/C technician certification by 1 Jan Use of EPA certified recovery and recycling equipment Recovery of both R-12 and R-134a refrigerants Prohibits mixing refrigerants Provides penalties including fines up to $27,500/day and 5 yrs. imprisonment. Industry has responded with changes and improvements to A/C systems and service procedures: Refrigerant R-12 is no longer produced or installed by manufacturers and R-134a is the only approved refrigerant installed by OEMs. By law, technicians must be properly trained and certified to work on mobile A/C systems. All refrigerants used in mobile air conditioners must now be recovered and recycled whenever an A/C system is opened for service or repair. A/C service equipment must be periodically maintained to reduce the possibility of refrigerant loss and inaccurate charge. Follow the service and maintenance schedule and instructions for your service equipment. Maintenance items vary but in general, periodic maintenance procedures are required for all service equipment. Typical service procedures for refrigerant recovery/recycling/recharging stations include: Vacuum pump oil change Filter/dryer cartridge replacement Checking the station for leaks Refrigerant storage tank scale accuracy check Climate Control Systems Diagnosis & Repair Page 1.3

10 A/C Refrigerant System Service & Diagnosis Manifold Gauge Set Service Ports on the Vehicle The port under the low side gauge connects the low side service hose to the low side service connection on the system. The low side service hose is always blue. The port under the high side gauge similarly connects the high side service hose to the high side service connection on the system. The high side service hose is always red. The center port on the manifold can be connected to either the red high side or blue low side service hoses when the respective hand valve is opened. The hand valves are opened ONLY when recovering, evacuating or recharging refrigerant from a system. Otherwise, the hand valves must be closed. Both high and low side gauges read system pressures with the hand valves on the manifold closed. A/C service stations have similar gauges and hand valves. They may appear different but in most cases they work the same way. The red and blue service hoses mate with the A/C refrigerant service ports on the vehicle. The high side and low side service port fitting quick connectors are different to prevent reversing the hose connections. The service port fittings have spring loaded check valves to prevent the loss of refrigerant. Dust caps keep the ports clean and are a secondary seal against refrigerant loss. For service port locations on the different models, see the individual model sections (Cayenne service ports shown above). Notes: Service hoses for R-134a systems have quick connectors and check valves to minimize refrigerant loss when connecting and disconnecting the hoses. Some hose connectors automatically depress the service port check valve pin. Other hose connectors have a knob which must be screwed clockwise after the hose is connected to manually depress the service port check valve pin. Page 1.4 Climate Control Systems Diagnosis & Repair

11 A/C Refrigerant System Service & Diagnosis A/C Refrigerant System Service Procedures The A/C service station recovers and stores the refrigerant while the system is being repaired. The service station must recycle the refrigerant so that it is pure for reuse. Finally the service station must remove all residual air and moisture from the system and then recharge it with an accurately measured quantity of refrigerant. The following information explains A/C service procedures. The information generally applies to all types of service stations. Be sure to consult the operating instructions for the specific service equipment that you are using and always follow the safety recommendations. Recovery To prepare for refrigerant recovery, be sure that the engine and A/C system are OFF. Attach the service hoses to the vehicle service ports. Open the service hose valves on the quick connectors if present (not all service hoses have them). Be sure that both high side and low side gauge hand valves on the service station control panel are closed. Check both gauges on the control panel before continuing. If the pressures are zero, the system is completely discharged and may contain air. DO NOT ATTEMPT RECOVERY as this will cause air to be drawn into the refrigerant storage tank. Note: Depending on the system you re running, deep vacuum is not created during recovery. If a deep vacuum were achieved, any water in the system would boil at room temperature and be pulled into the refrigerant storage container, contaminating the refrigerant and overloading the service station filter. Any moisture in the system will be removed later during evacuation, when a deep vacuum is reached. When the recovery operation is complete, close both high side and low side gauge hand valves on the service station control panel. Also close the storage tank valves. Oil Separator While recovering, approx cc ( oz.) of refrigerant oil may be removed from the system along with the refrigerant. After recovering, measure the quantity of oil in the oil separator. Follow the instructions for your machine. This is the minimum amount of oil that must be replaced with fresh oil when you recharge the system. If any component in the refrigerant circuit is replaced, more oil may have to be added, as the oil circulates throughout the system and coats the inside of every component. Notes: If the pressure gauges do not read zero, open both high side and low side gauge hand valves on the service station control panel. Open the storage tank valves as described in the operating instructions. Recover refrigerant per service station instructions. Most service stations will weigh the recovered refrigerant and indicate how much refrigerant was removed. Note this value as it can help diagnosis later. The recovery process creates a shallow vacuum of about 15 in.hg. in the A/C system. Usually the machine will turn off when this vacuum is reached. Wait five minutes and watch the low side pressure gauge to see if pressure rises. Often, pressure will rise because remaining refrigerant trapped in refrigerant oil, desiccant, etc. is now boiling off in the low pressure. If pressure rises above 0 in.hg., again perform the recovery. Repeat until pressure does not rise after five minutes. Climate Control Systems Diagnosis & Repair Page 1.5

12 A/C Refrigerant System Service & Diagnosis Evacuation Evacuation is the process of creating a deep vacuum of around 29 in. Hg. in the empty A/C system. Usually this is done after the system has been opened for repairs. Evacuation removes any air present and lowers the pressure in the A/C circuit to the point where moisture in the system boils at room temperature. This water vapor will then be removed by the vacuum pump. You should evacuate a system that has been opened for at least 15 min. to be sure all air and moisture is removed. For a quick and rough check for large system leaks, turn off the vacuum pump as soon as it reaches more than in.hg. Wait five minutes and observe the low pressure gauge. If gauge pressure rises, there is probably a large leak and there is no reason to continue evacuating until it is repaired. This method will not locate very small leaks. Leak detection methods will be discussed later. Reasons for evacuating the A/C system: Replacing PAG Oil Once the system has been evacuated and a deep vacuum exists, inject any required PAG oil. Follow the procedure for the machine you are using. See the Repair Information for the specified type of oil. Do not attempt to add oil to a system that is pressurized. The pressure will blow oil out of its container. Take care that the oil supply container does not run out of oil. If this occurs, air will be drawn into the A/C system and you will need to evacuate again. Always keep oil containers tightly sealed. PAG oil is hygroscopic and absorbs moisture very readily. Any container left open must be discarded and not used. When disposing, PAG oil should NOT be added to waste engine oils. Notes: The system was opened for service The system was opened by an accident or has been left open It is unknown whether the system has been open Part of a leak check procedure Refrigerant Recycling A/C service stations automatically recycle the recovered refrigerant during the evacuation process. The refrigerant is pumped continuously from the storage tank and passed through the filter/dryer. Usually no special steps need to be taken as long as the storage tank valves are open. A sight glass and moisture indicator will indicate the moisture content of the refrigerant and the effectiveness of the filter/dryer. Page 1.6 Climate Control Systems Diagnosis & Repair

13 A/C Refrigerant System Service & Diagnosis Recharging A/C systems can be recharged by two methods: Pumping liquid refrigerant into the system high side with A/C OFF. Allowing the A/C compressor to draw refrigerant gas into the low side with A/C ON. Most A/C service stations introduce liquid refrigerant on the system high side. Since the A/C compressor can be damaged by liquid refrigerant, you must be sure that the low side gauge hand valve is closed and the high side hand valve is open when recharging. This will allow refrigerant into the system high side only. The refrigerant will be distributed throughout the system once the system is started. The quantity of refrigerant to recharge is determined by weight. The specification is on a label in the engine compartment and also in the Workshop Manual Information. Be sure that the storage tank has sufficient refrigerant to charge the system. Modern A/C systems do not contain much refrigerant. so it is important to recharge the correct amount. To do this, the service station tank scale must be accurate. When recharging, be sure that the tank hoses are not stretched and do not bump, move or touch the machine or the storage tank. After the system is charged, turn the A/C ON with the engine idling. Be sure to close the service station high side gauge hand valve before turning the A/C system ON. If this valve is left open, the refrigerant storage tank will be exposed to high side pressures and can explode. A/C System Performance Testing An A/C system performance test should be performed before any service to verify a customer complaint of poor cooling performance. It should also be performed to verify that repairs have corrected the problem. Always be sure that the A/C system is mechanically OK before suspecting the electronics or controls. A general procedure for performance testing the A/C system includes the following steps. Always consult the Repair Information for model-specific procedures and specifications. Close doors, windows, and sliding roof. Insert temperature probe into center vent Measure ambient temperature Open all dash vents Switch ignition on Press recirculating air button Set temperature control to maximum cooling Switch fresh air blower to stage four Start engine Operate air conditioner while idling Set engine speed to 2000 RPM (start of time measurement) Compare the outlet air temperature with specifications. If the specified temperature is not obtained, follow diagnostic procedures in the service manual to determine the cause. The A/C system should be ON continuously for at least two minutes with the engine idling to properly distribute the refrigerant oil. Performance test the system as described in this section. When system performance has been verified, remove the service hoses. Recover the refrigerant in the hoses per the instructions and close the valves on the storage tank and control panel. Climate Control Systems Diagnosis & Repair Page 1.7

14 A/C Refrigerant System Service & Diagnosis Importance of a Diagnostic Plan Notes: A planned approach to the diagnosis of an A/C system problem can help you to locate problems faster. These steps are typical: Perform a performance test Check the DTC memory Check pressure gauge readings Note unusual refrigerant line temperatures Verify correct quantity of refrigerant Test system components The performance test will determine the nature of the problem and verify the complaint. Checking for stored DTCs will identify suspect components or systems, and whether the problem is likely to be electrical or mechanical. Pressure gauge readings will help to verify the mechanical integrity of the A/C circuit. With A/C ON, high pressure lines and components should be warm or hot. Low pressure lines and components should be cool or cold. If a component is frosted or much warmer or colder than normal, it could be plugged or defective. If refrigerant charge quantity could cause the symptoms noted, verify that the charge quantity is correct. Test any components that could cause the symptoms noted. Always follow procedures and use the specifications in the Workshop Manual. Page 1.8 Climate Control Systems Diagnosis & Repair

15 A/C Refrigerant System Service & Diagnosis Diagnosing with Pressure Gauges The A/C compressor is a pump that creates high side and low side system pressures. The compressor pumps against a restriction created by the expansion valve in order to raise high side pressures. Any mechanical fault in the system that prevents the compressor from pumping efficiently will result in pressures higher or lower than desired. The quantity of refrigerant also affects pressures. Checking high side and low side pressure can help to diagnose poor A/C performance. Remember that the compressor s job is to increase pressure on the high side and reduce pressure on the low side. Variable displacement compressors can compensate for many conditions and can make this diagnosis more difficult. Normal Pressures and Conditions Normal A/C pressures will vary with changes in temperature and humidity. In general, as the temperature and humidity increase, heat load and pressures also go up. Variable displacement compressors tend to keep low side pressures relatively constant. High side pressures go up and down with changes in heat load. The charts below show normal pressures for both fixeddisplacement and variable displacement compressors. Climate Control Systems Diagnosis & Repair Page 1.9

16 A/C Refrigerant System Service & Diagnosis Leak Detection A/C refrigerant leaks can be small and difficult to locate. Not all components are easily accessible and any component in the refrigerant circuit can potentially leak. When checking for leaks, pay close attention to connections, o-rings and seals. Electronic leak detectors can detect very small leaks for both R-134a and R-12 refrigerants. The detectors emit an audible signal when refrigerant is sensed. Refrigerant is heavier than air, so always place the probe under the component or connection when checking. Evaporator leaks can be checked by probing a low point, the evaporator moisture drain. Electronic leak detector sensitivity can be affected if the sensing tip is saturated with refrigerant or oil. Fluorescent dyes can be injected into the A/C system. The dyes mix with the system PAG oil and circulates with the oil. Oil may escape along with the leaking refrigerant and carry the dye along with it. An ultraviolet light (black light) causes the dye to glow and can help to locate the leak. Warnings and Cautions When servicing and repairing automotive climate control systems, you are exposed to several personal safety hazards. Be sure that you review and understand these potential hazards. Porsche Repair Information contains a list of safety precautions and warnings. Read and understand these warnings and cautions before starting diagnosis or repair work. Observe the following precautions: Automotive air conditioning systems and service equipment are under pressure and refrigerant can spray unexpectedly. Refrigerant temperatures may be very high or low, creating the risk of burns or frostbite. Be sure to wear gloves and eye protection conforming to ANSI standard Z87. Never open a charged A/C system before recovering the refrigerant. An operating A/C system can generate pressures up to 34.5 bar (500 psi). Work in a well ventilated area. Refrigerants R-12 and R- 134a both displace oxygen and are a suffocation hazard. Refrigerants are heavier than air and can collect in low areas with poor air circulation, such as under the vehicle. Do not heat charged air conditioning system components to temperatures above 80 C (176 F). Pressure increases from high temperatures may cause the system to burst. Store refrigerant containers at temperatures below 50 C (122 F). When charging an A/C system, do not heat containers with an open flame. Use only warm water to raise the temperature of refrigerant containers. Before welding or soldering A/C components, recover all refrigerant and flush the system with nitrogen. Refrigerants decompose with heat and produce corrosive substances. A pungent odor indicates that these substances are present. Do not inhale. They can cause respiratory problems. Although refrigerant R-12 is not combustible, it produces poisonous phosgene gas when burned. Do not smoke where refrigerant vapor may be present. R-12 entering the engine's air intake will likely be burned in the combustion chamber. Page 1.10 Climate Control Systems Diagnosis & Repair

17 A/C Refrigerant System Service & Diagnosis R-134a is not normally combustible, but at pressures above ambient and mixed with excess air, it can be flammable. Do not use compressed air to blow out A/C refrigerant components or containers unless all of the refrigerant has been recovered and the component has been completely removed from the refrigerant circuit. By law, containers used for recovered refrigerant may be filled to 60% of capacity max. Only use approved containers to recover refrigerant. Secure refrigerant containers from falling. Containers can deform and burst. or the valves can break off. Do not steam clean A/C condensers or evaporators. The added heat can cause a dangerous increase in refrigerant pressures. The engine cooling system is pressurized. Use care when removing the pressure cap. All current production Porsches use electric cooling fans actuated by coolant temperature. These fans will come on at any time when coolant temperatures exceed a certain value. See Workshop Manual for specifications. For safety, most charging stations recharge A/C systems by pumping the refrigerant into the system with the compressor not running. Make sure the high side manifold gauge valve is always closed whenever the compressor is running. Service Equipment Safety The hand valves on the manifold pressure gauges are opened to connect the red or blue Service Hoses and the Manifold Center Port. The Manifold Center Port is only used when discharging, evacuating or recharging the system. All other times, the hand valves are closed. Fittings for R-134a service equipment are different from those used on R-12 systems. This is to prevent crosscontamination of refrigerants. Mixed refrigerants cannot be reused and become hazardous waste that must be disposed of properly. R-134a service equipment uses quick connect fittings to minimize the discharge of refrigerant when connecting and disconnecting the hoses. R-12 service equipment uses threaded fittings and hand shut-off valves to contain refrigerant in the lines. By law, the shut-off valves must be placed no more than 12 inches from the ends of the service hoses to reduce refrigerant loss. Climate Control Systems Diagnosis & Repair Page 1.11

18 A/C Refrigerant System Service & Diagnosis First Aid If refrigerant contacts eyes or mucous membranes, rinse immediately with large quantities of water and seek medical attention. If refrigerant contacts the skin, remove the wet clothing and rinse immediately with large quantities of water. Seek medical attention if required. If concentrated refrigerant vapor is inhaled, give the person fresh air immediately. Seek medical attention if there is difficulty in breathing. Page 1.12 Climate Control Systems Diagnosis & Repair

19 Air Conditioning Basics Subject Page Air Conditioning Overview Principles of Heat Transfer The Refrigeration Cycle Compressor Pressure Relief Valve Condenser Receiver/Dryer Evaporator Thermostatic Expansion Valve Lines and Hoses Service Connections Refrigerants Climate Control Systems Diagnosis & Repair Page 2.1

20 Air Conditioning Basics Notes: Page 2.2 Climate Control Systems Diagnosis & Repair

21 Air Conditioning Basics Air Conditioning Overview Air conditioning is the process of moving heat energy from one place in the vehicle to another. Doing this raises or lowers the temperature of the air in the vehicle interior. The A/C system is a closed loop system in which a refrigerant is pumped by the compressor through the circuit continuously. While it is being pumped, the refrigerant changes state from liquid to gas and back again. The refrigerant changes from liquid to gas in the evaporator as it removes heat from the passenger compartment. Then the refrigerant gas condenses back to liquid in the condenser, giving off heat to ambient (outside) air. This is a short description of how A/C works. These concepts will be discussed in more detail in the next section. Principles of Heat Transfer There are four principles of heat and heat transfer that apply to automotive heating, air conditioning and climate control systems: 1. Heat always flows from hot to cold. 2. Materials absorb or give off large amounts of heat when changing state. 3. The pressure of a liquid or gas varies with its temperature and the temperature of a liquid or gas varies with its pressure. 4. The boiling point of a liquid varies with its pressure. Climate Control Systems Diagnosis & Repair Page 2.3

22 Air Conditioning Basics 1. Heat always flows from hot to cold. 2. Materials absorb or give off large amounts of heat when changing state. Sweating makes us feel cooler. As liquid water on our skin evaporates, it removes body heat. In a similar way, refrigerant vaporizing (changing from liquid to gas) inside the A/C evaporator absorbs heat from the warmer air around the evaporator. Practical Application Heat is a form of energy. Cold is a term that means less heat is present. Cold materials contain less heat energy than hot materials and heat always flows from the hotter material to the colder. For example, if you hold an ice cube, your hand will feel cold. The ice removes heat from your hand and you sense the loss of heat. If you touch something warm, you feel the heat flowing into your hand. If a large amount of heat transfers, you may be burned and feel pain. Practical Application Heat energy contained in the passenger compartment air is absorbed by the cold refrigerant in the A/C evaporator. Hot refrigerant gives off heat and is cooled by cooler ambient air flowing through the A/C condenser. In both cases, heat moves from hotter to cooler. Notes: In the evaporator, liquid refrigerant boils at temperatures below the temperature of the air in the passenger compartment. The refrigerant absorbs large quantities of heat, far more heat than it would if it remained a liquid. In the condenser, the reverse takes place. Here, hot refrigerant gas condenses back to liquid and gives off large amounts of heat to the cooler atmosphere. The refrigerant gives up far more heat than it would if it remained a gas. To explain, we need to look at two kinds of heat energy: Sensible Heat and Latent Heat. Sensible Heat is measurable heat - a measurable change in the temperature of a material. Adding heat energy raises the measurable temperature of a material and increases Sensible Heat. If we heat a pot of water on a stove, the temperature of the water will increase and we can measure this change with a thermometer (see illustration, below). Heat energy increases temperature of liquid No change of state Sensible Heat Page 2.4 Climate Control Systems Diagnosis & Repair

23 Air Conditioning Basics Latent Heat is heat energy that is added to a material causing it to change state. The temperature of the material remains the same during the change of state. We can raise the temperature a pot of water to the boiling point (100 C/212 F) by adding Sensible Heat energy, but to make the water boil and change state from liquid to gas, it takes much more heat energy in the form of Latent Heat. Similarly, when a gas condenses to a liquid, large amounts of Latent Heat energy are released (see illustration, below). The unit of heat energy is the BTU (British Thermal Unit). One BTU = the amount of heat energy required to raise the temperature of one pound of water one degree F. At sea level pressure, water boils at 212 F. In order to raise the temperature of one pound of water from 211 F to 212 F, only one BTU heat energy is needed. But to change that same pound of water at 212 F to one pound of steam (gas) at 212 F requires 970 BTUs, a much greater quantity of heat. When the water condenses back to a liquid, it gives off the same 970 BTUs of heat. In the A/C system, refrigerant evaporates and condenses over and over as it is pumped through the system. R-134a refrigerant absorbs or gives off large amounts of latent heat energy (about 85 BTU/lb) as it changes state. This is the key to the efficiency of A/C systems. 3. The pressure of a liquid or gas varies with its temperature and the temperature of a liquid or gas varies with its pressure. The pressure of the refrigerant in the closed A/C circuit will vary with changes in temperature, and the temperature of the refrigerant varies with changes in its pressure. With A/C off and at an ambient temperature of 21 C (70 F), the pressure in a fully charged system will be approximately 4.8 bar (70 psi). As the temperature rises, the pressure will also rise. The table below shows the temperature/pressure relationship for R-134a at temperatures between -30 C (-22 F) and 70 C (158 F). At -30 C (-22 F) refrigerant pressure drops to 0 bar (0 psi). At this temperature, liquid refrigerant in an open container will not boil and will remain a liquid. Practical Application The job of the A/C compressor is to compress refrigerant gas, raising its pressure and temperature and concentrating the heat. The refrigerant flows to the condenser where it is much hotter than the ambient air blowing through and gives up latent heat to the air. Heat energy changes liquid to vapor (gas) Temperature of liquid does not change. Change of state occurs In the evaporator, refrigerant is exposed to low pressure. This lowers its temperature and the cold refrigerant absorbs latent heat from the passenger compartment. Note: The temperatures of the A/C lines when the A/C is ON. The high pressure lines will be warm or hot, the low pressure lines will be cool or cold. Latent Heat R-134a Refrigerant Pressure vs. Temperature Climate Control Systems Diagnosis & Repair Page 2.5

24 Air Conditioning Basics 4. The boiling point of a liquid varies with its pressure. The boiling point of a liquid changes with pressure. For example, engine coolant temperatures can easily climb above the boiling point of the coolant/water mixture at sea level pressure, about 108 C (226 F). By increasing the pressure to 1 bar (15 psi) the boiling point is raised to 128 C (263 F). Practical Application higher altitudes, such as in Denver, the pressure is lower, and therefore the boiling point is lower. This is why baking or cooking times are longer at high altitudes. On the table, note the low pressure at which water will boil at room temperature (shown in bold). This low pressure is attained during refrigerant system evacuation. At this low pressure, any water present in the A/C system will boil off. Notes: When the A/C system is operating, the refrigerant pressure in the evaporator is low which lowers its boiling point. This allows the liquid refrigerant to boil and to change state to a gas, absorbing latent heat. In the condenser, the pressure of the refrigerant gas is high, raising the boiling point and allowing it to condense to liquid as heat is removed. R-134a refrigerant is as a gas at atmospheric pressures and ambient temperatures. In the closed refrigerant circuit, some refrigerant is in liquid form because of the higher pressure. As with water, the boiling point of refrigerant increases as its pressure increases. Reducing pressure to below-atmospheric (partial vacuum) lowers the boiling point of a liquid. The table shows the boiling point of water at several low pressures. The value in. Hg is atmospheric pressure at sea level. At this pressure, the boiling point of water is 100 C (212 F). At Page 2.6 Climate Control Systems Diagnosis & Repair

25 Air Conditioning Basics The Refrigeration Cycle As we have said, air conditioning is the process of moving heat energy from one place in the vehicle to another. The A/C system is a closed system in which the compressor pumps the refrigerant through the circuit over and over whenever the A/C is ON. While it is being pumped, the refrigerant changes state from liquid to gas and back again. The refrigerant changes from liquid to gas in the evaporator as it removes heat from the passenger compartment. Then the refrigerant gas condenses back to liquid in the condenser, giving up heat to ambient (outside) air. The refrigerant does not get worn out or used up unless there is a mechanical problem or a leak. The amount of heat moved from inside to outside the vehicle determines the heat load. Both temperature and humidity affect the heat load. The refrigerant circulates in the closed circuit made up of these components: High and Low Pressure Sections The system is divided into high pressure and low pressure sections. They are the "high side" or discharge (D), and "low side" or Suction (S). The compressor is the pump that raises refrigerant pressure on the high side of the system and reduces pressure on the low side. The compressor and the expansion valve separate the two sides of the system. The condenser and receiver dryer are always on the system high side. The evaporator is always on the system low side. Notes: Compressor Condenser Receiver/Dryer Thermostatic Expansion Valve Evaporator Lines and Hoses Refrigerant Regulation and Control Devices Climate Control Systems Diagnosis & Repair Page 2.7

26 Air Conditioning Basics Compressor Reed valves are flat plates of spring material located in the cylinder head above each piston. They bend one way only and allow flow in one direction. They open and close automatically in response to pressure changes as the pistons travel up and down. The compressor is an engine-driven refrigerant pump. It compresses the refrigerant gas to raise both temperature and pressure. The compressor also moves refrigerant through the system. All Porsche Sports Cars and Cayenne A/C compressors are variable displacement swash plate designs. Fixed displacement compressors were used on 911 Carrera (993) and earlier models. The compressor is belt driven. On Sports Cars an electromagnetic clutch is built into the compressor pulley to engage and disengage the drive. On Cayenne, there is no clutch. The compressor shaft turns at all times with the engine. When no A/C is desired, compressor displacement can be reduced to nearly 0%. Compressor piston downstroke draws in low pressure refrigerant gas from the evaporator. On the upstroke, the refrigerant is compressed, raising both pressure and temperature. Refrigerant pressure increases from approx bar (9-25 psi) to approx bar ( psi). The compressed refrigerant gas is pushed out of the compressor to the condenser. The compressor can raise the pressure of the refrigerant because it is pumping against a restriction created by the expansion valve. The system high side contains high pressure refrigerant, and includes the compressor outlet, condenser, receiver-dryer and expansion valve inlet. The flow of refrigerant gas into and out of the compressor is controlled by reed valves. The reeds are designed to pump refrigerant gas only, and the compressor pistons have little clearance at the top of their stroke. Liquid refrigerant must be kept out of the compressor as it can hydraulic lock and damage it. Fixed Displacement Compressors Fixed displacement compressors have a fixed piston stroke and always pump the same volume of refrigerant for each revolution of the compressor shaft. The piston stroke never varies and the compressor's displacement never changes. All A/C compressors must have sufficient capacity for good cooling under high heat load conditions and low engine speeds. Since fixed displacement compressors cannot vary the amount that they pump, under conditions with high engine speed and low heat demands, these compressors have much greater capacity than is required. Energy can be wasted pumping this excess refrigerant. Also, the compressor clutch may cycle ON and OFF more frequently than is desired. Notes: Page 2.8 Climate Control Systems Diagnosis & Repair

27 Air Conditioning Basics Variable Displacement Compressors Porsche vehicles today use a variable displacement compressor. Seven axial pistons are arranged concentrically around the central compressor shaft. A smooth disk is attached to the compressor shaft. Slipper shoes follow the disk's oscillating motion and the angle of the disk transmits reciprocating forces to the pistons. Variable displacement compressors can vary the piston stroke and can change output volume. The longer the piston stroke, the greater the displacement and output. The stroke is determined by the angle of the swash plate on the compressor shaft. Variable displacement compressors change the swash plate angle to match the refrigerant flow rate to the heat load on the system. Variable displacement compressors are more efficient than fixed displacement compressors because they pump only enough refrigerant to achieve the desired cooling. Energy is not wasted pumping more refrigerant than is necessary. Also, clutch cycling is eliminated and engine idling is improved with variable displacement compressors. Heat Load The compressor senses system refrigerant pressures to determine heat load and automatically adjust the volume of refrigerant pumped for optimum heat transfer. The output of the compressor varies between 5% and 100%. Compressor displacement is 160 cm 3 at 100% output. Low Heat Load - 5% Output The conditions are met when engine r.p.m. is consistently high, e.g. expressway driving, and/or temperature is low. The suction pressure is relatively low and the control valve is open. The angle of the rotating disk is at its lowest and so delivery is at its minimum. High Heat Load - 100% Output Sports Cars Variable Displacement Compressor, Low Displacement Position The conditions are met when engine r.p.m. is consistently low and/or temperature is high. The suction pressure is high and closes the control valve. The angle of the rotating disk is at its greatest and so delivery is at its maximum. Notes: Sports Cars Variable Displacement Compressor, High Displacement Position Climate Control Systems Diagnosis & Repair Page 2.9

28 Air Conditioning Basics Mechanical Regulating Valve Porsche Sports Cars up to MY 2008 use variable displacement compressors with mechanical regulating valves. Cayenne MY on and Sports Cars as of MY 2009 have a variable displacement compressor controlled by a PWM electronic control valve. Both types regulate compressor displacement by changing pressure in the crankcase under the pistons. Pressure Relief Valve Lubrication All A/C compressors require oil for lubrication. The oil reduces internal friction and heat and helps to seal moving parts. This lubricant is carried by the flow of refrigerant throughout the system and it must be compatible with the refrigerant, seals and components. Porsche A/C systems with R-134a refrigerant use synthetic PAG (polyalkylene glycol) or ester oil. R-12 systems use mineral oil. These oils are not compatible. Mineral oil will not mix with R-134a refrigerant and must not be used in R-134a systems. Since the oil flows with the refrigerant throughout the system, a portion of the total oil charge must be replaced when any component is replaced. Some oil may also be removed along with the refrigerant when discharging a system. A/C service stations have provisions for capturing and measuring any oil removed so that an equal amount can be restored. A typical system contains approx. 195 cm3 (6.6 oz.) of ND8 PAG oil. Refer to Service Information for specifications regarding the amount of oil to add for each system component. Porsche A/C compressors have a spring loaded mechanical pressure relief valve. If system pressures get dangerously high, the valve will open and vent the excess pressure. The valve closes when pressures have dropped to safe levels to prevent the complete loss of refrigerant. Opening pressure is approximately 38 bar (550 psi). The valve will close when pressures have dropped to approximately bar ( psi). Removal of the pressure relief valve first requires recovery of the refrigerant from the system. Caution: Always store refrigerant oil in closed containers. These oils are very hygroscopic, that is, they readily absorb moisture. Never reuse refrigerant oil from a system. Always replace with fresh uncontaminated oil. Always consult the Repair Information for the correct oil specification and quantity. Page 2.10 Climate Control Systems Diagnosis & Repair

29 Air Conditioning Basics Condenser Receiver/Dryer The condenser is a heat exchanger located in the front of the vehicle. It is similar to the engine radiator and has a large surface area for efficient heat transfer. Some Porsche models use two condensers. The condenser is on the A/C system high side and contains high pressure refrigerant. The condenser allows high pressure, hot refrigerant gas to give off heat energy to cooler air passing through the condenser fins. Forward motion of the vehicle and electric fans both promote this air flow. The refrigerant changes state in the condenser in this sequence: High pressure refrigerant enters the condenser as a hot gas: C ( F). The heat energy that was absorbed by the refrigerant in the evaporator is transferred to the cooler ambient air passing over the condenser's tubes and fins. The refrigerant gas gives up both sensible heat and large amounts of latent heat energy to the cooler ambient air. The gas cools, changes state and condenses to a liquid. The refrigerant leaves the condenser as a very warm high pressure liquid. The DME controls system cooling fans based on engine load. When the A/C is ON, the electric cooling fan comes ON to improve airflow and heat transfer. 911 Carrera (996) Receiver/Dryer The receiver/dryer is a reservoir for refrigerant on the system high pressure side. It is located between the condenser outlet and evaporator inlet. Condensed liquid refrigerant flows into the receiver dryer from the condenser. As heat load on the A/C system changes, more or less refrigerant will be in the liquid state. Also, over time, some refrigerant will escape past seals. The receiver/dryer acts as a reservoir for refrigerant to compensate for these conditions. The pickup tube in the receiver/dryer ensures that only liquid refrigerant is sent to the expansion valve. The receiver/dryer contains a desiccant to remove moisture from the system. The desiccant can absorb 6-12 g of water. This is not much, and moisture must be kept out of the system during repairs. R-12 systems included a sight glass on top of the receiver/dryer The flow of liquid refrigerant could be seen through the glass and a stream of bubbles indicated low refrigerant level. A sight glass was used on some R-134a systems in the early 1990 s. A/C service equipment accurately measures the refrigerant charge by weight, making the sight glass unnecessary. When retrofitting an R-12 system with R-134a, always replace the receiver/dryer as R-12 desiccants are not compatible with R-134a, and the desiccant will be permanently saturated with mineral oil. Climate Control Systems Diagnosis & Repair Page 2.11

30 Air Conditioning Basics Evaporator In addition to removing heat, the evaporator also dehumidifies the interior air. Cool air cannot hold as much moisture as warm air. As the air is cooled, moisture condenses and collects on the evaporator fins. Dehumidifying the air adds to passenger comfort and also helps to demist the windshield in damp weather. This is why A/C is enabled when the defrost function is selected. Evaporator fin temperatures cannot be allowed to drop below the freezing point of water, 0 C (32 F), or the condensation can freeze and ice buildup can block the evaporator fins. Dust and matter carried in with the airstream tends to collect on the wet evaporator fins, so there is a cleaning effect. The condensed water that collects on the evaporator fins is allowed to drain. The evaporator is a heat exchanger located in air distribution housing. It has tubes and fins similar to a radiator or condenser and it has a large surface area for efficient heat transfer. The evaporator permits cold refrigerant to absorb heat from warm air in the passenger compartment. Outside air or recirculated air is forced through the air distribution housing and evaporator fins by blowers. Notes: The evaporator is on the A/C system low pressure side. The thermostatic expansion valve (TEV) is a restriction controlling how much refrigerant enters the evaporator. The refrigerant changes state in the evaporator in this sequence: Liquid high pressure refrigerant sprays into the evaporator, controlled by the TEV orifice. The pressure of the refrigerant drops as it passes through this orifice. At this low pressure, the refrigerant temperature is above its boiling point. The refrigerant boils rapidly and changes state. As the refrigerant becomes a gas, it absorbs both sensible heat and large amounts of latent heat from the cabin air passing through the evaporator fins. The refrigerant warms and the cabin air passing over the evaporator fins cools. The refrigerant leaves the evaporator as a cool low pressure gas, pulled by the suction (intake) side of the compressor. This low side pressure will be approx. 2 bar (30 psi). Check workshop manuals for exact system pressure specifications. Page 2.12 Climate Control Systems Diagnosis & Repair

31 Air Conditioning Basics Thermostatic Expansion Valve (TEV) The Thermostatic Expansion Valve (TEV) is located at the evaporator inlet. It separates the high and low pressure sides of the system and creates the restriction that the compressor uses to build high side pressure. High pressure liquid refrigerant flows to the expansion valve inlet from the receiver/dryer. Porsche uses the H-Type block expansion valve. This valve works the same way as the old style right-angle valve with external sensing tubes, but is internally compensated within the valve and has no external lines to the evaporator. The TEV has a variable orifice which controls the amount of refrigerant admitted into the evaporator. High pressure liquid refrigerant passes through the TEV orifice at the evaporator inlet. The liquid refrigerant sprays into the evaporator where it is exposed to low pressure and rapidly evaporates. The TEV senses both temperature and pressure in the evaporator. Both evaporator inlet and outlet lines pass through the TEV. Refrigerant temperature is sensed at the evaporator outlet. Increases in evaporator outlet gas temperature due to increased heat load cause the diaphragm in the gas filled thermostatic valve element to move downward, opening the ball valve a greater amount against spring tension and admitting more refrigerant. The expansion valve also senses evaporator inlet pressure. Pressure acts on the underside of the diaphragm in the gas filled thermostatic valve element. Any decrease in evaporator pressure tends to open the ball valve and increase the amount of refrigerant admitted. This would be the case if the evaporator were "starved" and required more refrigerant. When additional refrigerant flows into the evaporator, more refrigerant is available to absorb heat. This reduces the temperature at the evaporator outlet, causing a pressure drop in the thermostatic valve element and increases evaporator pressure. Both conditions act on the diaphragm to reduce the ball valve opening. The cross-section opening of the valve is reduced as the spring pushes the ball valve toward its seat. Notes: Climate Control Systems Diagnosis & Repair Page 2.13

32 Air Conditioning Basics Lines and Hoses A/C system components are connected by rigid lines and flexible hoses. This creates the closed loop through which the refrigerant flows. Rigid lines are formed aluminum. The flexible hoses are a reinforced rubber compound with a barrier liner. Low pressure lines and hoses are generally larger in diameter when compared with high pressure lines and hoses. This is because refrigerant gas in the low side has expanded and takes up much more space than either refrigerant gas or liquid on the high side. Joints may be several types but always have o-rings for sealing. When assembling lines or replacing o-ring seals, always lubricate o-rings only with PAG oil. The oil helps the o-ring to properly seat and seal. Do not use any other lubricant. Always torque fasteners to specifications. Service Connections 911 Carrera (993) models have A/C high and low side service connections located in the rear near the A/C compressor. Cayenne model service connections are in front in the engine compartment on the left side. R-134a service connection fittings are quick-connect style and are different from those on R-12 systems. This was done to prevent cross-contamination of refrigerants which cannot be mixed. R-134a quick connect fittings are different sizes for the high and low sides. This ensures that the low side and high side service hoses are properly connected to their respective ports. Disconnecting an R- 134a service hose quick-connector automatically seals the ports to retain the refrigerant in the vehicle s system and also in the service hose. R-12 systems use threaded service connection fittings and hand shut-off valves. By law, the shut-off valves must be no more than 30 cm (12 in.) from the end of the service hose to reduce refrigerant loss. 911 Carrera (996)/(997) and Boxster (986)/(987) model connections are located in the cowl area on the right side, near the battery and expansion valve. Page 2.14 Climate Control Systems Diagnosis & Repair

33 Air Conditioning Basics Refrigerants The refrigerant is the substance that is pumped by the compressor through the closed system to transport heat from one place to another. The refrigerant changes state from a liquid to a gas and back again as it cycles. It does not wear out or get used up unless it gets contaminated. Refrigerant R-12 (Dichlorodifluoromethane, trade name FREON) was the refrigerant used in vehicles for decades. R-12 was considered completely inert, safe and harmless, but it is a CFC or Chlorofluorocarbon. CFCs contains Chlorine which is suspected of damaging the ozone layer and contributing to global warming. R-12 is no longer produced in this country, and Porsche discontinued its use in R-134a (Tetrafluoroethane, trade name SUVA) is the refrigerant used today. It has similar heat transfer properties like R-12 but it does not contain Chlorine. R-134a has 84% less global warming potential than R-12 and it does not destroy ozone. For these reasons, R-134a has been judged to be better for the environment. R-134a is the only approved refrigerant and the only approved replacement for R-12. R-134a and R-12 refrigerants are not compatible and will not mix. Cross-contamination must be avoided when servicing the A/C system. To reduce the possibility of errors, refrigerant storage containers are different colors (white for R-12 and light blue for R-134a), and fittings are different. Mixed refrigerants are a hazardous waste that must be disposed of properly. As mentioned before, the lubricating oils are different for each refrigerant. R-12 systems use mineral oil and R-134a systems use synthetic PAG or ester oils. Note: Refer to Equipment Bulletins for recomendation of a refrigerant tester that can analyze the refrigerant used in a vehicle. Notes: Climate Control Systems Diagnosis & Repair Page 2.15

34 Air Conditioning Basics Notes: Page 2.16 Climate Control Systems Diagnosis & Repair

35 Sports Cars Systems Subject Page Sports Cars Systems 9x6 & 9x7 A/C Systems General Information System 1 Description Boxster (986) & 911 (996) Refrigerant System Description Air Distribution System Regulating Air Temperature Control Panel Function, 911 Carrera (996) & Boxster (986) Sensors and Actuators Sensors Actuators Service and Diagnosis Information On Board Diagnostics System 2 Description Boxster/Cayman (987) & 911 (997) up to 2008, 911 Turbo up to 2009 Manual Air Conditioning, Boxster/Cayman (987) Automatic Climate Control, 911 Carrera/S (997) Optional Boxster/Cayman (987) Interior Sensor Cooling Fans Service and Diagnosis Information Information Transmitted Via CAN Interface System 3 Description Boxster/Cayman (987) & 911 (997) as of 2009 (except 911 Turbo) Externally Controlled Compressor Variable PWM System Operation Evaporator Temperature Sensor Ventilated Seats Steering Wheel Heating Climate Control Systems Diagnosis & Repair Page 3.1

36 Sports Cars Systems Notes: Page 3.2 Climate Control Systems Diagnosis & Repair

37 Sports Cars Systems Sports Cars 9x6 & 9x7 A/C Systems Boxster (986) MY Carrara (996) MY Boxster/Cayman (987) MY Carrera (997) MY 2005 to 2008 (including GT3) 911 Turbo (997) MY 2007 to 2009 (including GT2) General Boxster (986) & 911 (996) The automatic climate control system automatically maintains the selected passenger compartment temperature. The system is capable of maintaining temperatures between C (64-84 F), with 22 C (72 F) recommended. In automatic operation, the system determines and controls blower speed, outlet air temperature, and outlet selection. The automatic climate control system also permits manual selection of temperature and air distribution if desired. General Boxster (987) MY Cayman (987) MY The Boxster/Cayman (987) series feature manual air conditioning with combined interior filter (active carbon and pollen filter) as standard equipment. Automatic climate control is available as an option. Both systems; air conditioning and automatic climate control are further developments of the respective previous systems. They have been revised to ensure more even and more comfortable ventilation of the passenger area and to improve the user friendliness of all air conditioning functions. General 911/GT3 (997) MY Turbo/GT2 (997) MY In contrast to the previous 911 (996), the 911 (997) series featured automatic climate control with a combined interior air filter (active carbon and pollen) as standard. The automatic climate control used in the 911 (997) is a further development of the previous 911 (996) system. It was revised to ensure more even and more comfortable ventilation of the passenger area and to improve the userfriendliness of all air conditioning functions. The advantages of the new air conditioning systems: Ensures more even ventilation of the passenger area Is considerably less prone to drafts Is quieter and offers increased functionality The air conditioning system employs a CFC-free refrigerant. In order to ensure an adequate supply of electrical energy (taking additional facilities into consideration), the 70 Ah battery is more powerful than its predecessor and has been weight optimized. General 911 Carrera/S (997) MY 2009 The 911 Carrera (997) series are the first sports cars to feature the externally controlled compressor system. With an externally controlled system, the air conditioning operating panel has a direct effect on the compressor and thus on the cooling output. Given this, most changes here relate to the compressor or compressor control. The components, which you will be familiar with from the air-conditioning system used in the previous model, are not modified to any great extent by this system and are essentially identical from the point of view of design and operating principle. A comparable externally controlled compressor system is also used in the Cayenne. Advantages of an externally controlled compressor: Reduced weight due to removal of a compressor clutch Total weight loss here: approx. 3 lbs. (1.4 kg) No need to push the clutch when engaging (high-comfort use) Refrigerant output is controlled more precisely and is demand-controlled, based directly on the evaporator temperature Climate Control Systems Diagnosis & Repair Page 3.3

38 Sports Cars System 1 (9x6) Sports Cars 9x6 A/C System Description Boxster (986) & 911 (996) Compressor Condensers Two A/C condensers are used on the Boxster (986) and 911 (996) models. They are mounted in the front of the vehicle on the left and right-hand sides in front of the engine coolant radiators. Each condenser is cooled by the electric cooling fan to ensure sufficient airflow and heat transfer under all driving conditions. Refrigerant flows through the right side condenser first, then the left. Receiver Drier The A/C compressor is a continuously variable 7-cylinder swash plate design. An internal mechanical regulating valve varies compressor displacement by changing pressure in the crankcase under the pistons. The regulating valve senses changes in refrigerant high side and low side pressures. These pressures are an indication of heat load: high displacement for high heat load, low displacement for low heat load. The compressor displacement is 160 cm 3 (9.8 in 3 ) at 100% output. Output can be as low as approx. 5%. The refrigerant tank is installed in the fresh air chamber at front left, next to the battery. The pressure relief valve (see arrow) for the refrigerant system is also located here. Page 3.4 Climate Control Systems Diagnosis & Repair

39 Sports Cars System 1 (9x6) Evaporator The A/C evaporator is located in the air distribution housing. Evaporator removal requires removal and disassembly of the air distribution housing. Thermostatic Expansion Valve (TEV) The H-Type block Thermostatic Expansion Valve (TEV) is located at the evaporator inlet in the cowl area on the right side of the battery. Service Connections Air Distribution System The air distribution system controls air volume, temperature and direction within the passenger compartment. The system can add or remove heat from the cabin air and provide ventilation, heating, cooling and defrost functions. On Boxster (986) and 911 (996) models, the water cooled engine allows the use of a heater core with hot engine coolant to add heat to the interior. The air distribution housing contains the evaporator, heater core, blower fan, air control flaps and their actuators, and passages to various air outlets in the vehicle. The air distribution housing mixes fresh (outside) air, recirculated air, cooled air and heated air to obtain the desired interior temperature. A blower distributes this air to the system outlets. Air and Flap Controls (heater box) Service connections are located in the cowl area on the right side, near the battery and expansion valve. Notes: 1 - Fresh air intake port 2 - Fan motor 3 - Fan regulator / output stage 4 - Central distributor flap 5 - Heat exchanger 6 - Evaporator 7 - Expansion valve (on rear side) Climate Control Systems Diagnosis & Repair Page 3.5

40 Sports Cars System 1 (9x6) Recommended air distribution: Regulating Air Temperature The air distribution housing is attached to the bulkhead under the instrument panel. The housing includes the evaporator, heater core, blower, air control flaps and actuators, ducts and outlets. Fresh air enters the intake duct in front of the windshield. All air entering the air distribution housing first passes through the evaporator where, with A/C ON, the air is cooled more than desired and dehumidified by the cold evaporator. 1 - Fresh air intake port 2 - Distributor flap for fresh air/recirc. air 3 - Recirculating air intake port 4 - Fan motor 5 - Evaporator 6 - Temperature mix flap 7 - Heat exchanger 8 - Defrost air outlet vent 9 - Footwell/defrost distributor flap 10 - Footwell air outlet vent 11 - Central distributor flap 12 - Central and side vents In summer Air distribution to central and side vents In winter Air distribution to the footwell and the front windshield Back Pressure Compensation The air throughput is influenced by the back pressure which arises in the area of the fresh air inlet according to the vehicle speed. In order to compensate for this dependency, the distributor flap for fresh air/recirculated air (back pressure flap) is moved in the direction of closed (recirculated air) according to the vehicle speed (from 55 mph/90 km/h). The flap setting is also dependent on the fan voltage. Page 3.6 Climate Control Systems Diagnosis & Repair

41 Sports Cars System 1 (9x6) After passing through the evaporator, the cooled airflow splits. Some of this air is directed through the hot heater core and is reheated, the rest bypasses. Outlet temperature is directly related to the percentage of air directed to the heater core. A temperature flap controls how much air is sent through the heater core. If heating the incoming air is not desired, then the temperature flap can be set to bypass all air around the heater core and no reheat will take place. This occurs with the Max. A/C setting. Air Recirculation Mode Depressing the recirculation switch on the A/C Control Unit selects the recirculation mode. The recirculation mode prevents outside air intake and increases the cooling efficiency of the A/C. It also prevents unpleasant odors from entering the vehicle interior. When ambient temperature is > 26 C (79 F), the processor automatically selects the recirculation mode after 30 seconds of A/C operation to speed interior cooling. Manual air recirculation can be selected at any time to prevent unpleasant odors from entering. The recirculation mode is limited to 2 minutes max. if the A/C compressor is OFF. Defrost Mode Depressing the defrost button on the Heating-A/C Control Unit selects the defrost mode. This mode directs most outlet air to the windshield. Air conditioning is engaged to reduce humidity and to speed demisting. Notes: Fresh Air Mode Air can be drawn into the air distribution housing from two sources: outside (fresh) air, and inside (recirculation) air. When the fresh air mode is selected, outside air is drawn into the vehicle from the intake air duct, located in the plenum in front of the windshield. All outside air passes through the particle filter. As vehicle speed increases, ram air pressure increases airflow. To compensate, the ram flap begins to close > 56 mph. The ram flap position is also influenced by blower voltage. Climate Control Systems Diagnosis & Repair Page 3.7

42 Sports Cars System 1 (9x6) Particle Filter A particle filter is installed in the fresh air inlet on the right side of the cowl. All fresh air passes through this filter. An optional charcoal filter can also be installed. The filter removes airborne matter, and the optional charcoal filter also absorbs pollutants and odors. The filter should be replaced during specified service intervals. A/C Control Unit Function Boxster (986) and 911 (996) models Ventilation In the Boxster (986), the ventilation system for the passenger compartment also modifies the temperature of the rear trunk, as interior air is constantly ventilated to the outside through the trunk. Air exits the passenger compartment through vents in the rear deck into the trunk. Vents in the sides of the trunk allow air to exit through oneway flaps. 911 (996) models expel air forwards through passages in the side sills, through one-way flaps exiting into the front wheel wells. The front wheel wells act as low pressure areas while driving, and increase airflow out of the vehicle. Automatic climate control was standard equipment on Boxster (986) and 911 (996) models sold in the United States. The system automatically maintains temperatures between C (64-84 F) (with 22 C (72 F) recommended). The A/C Control Unit is located in the dash and has the passenger s controls. In automatic operation, the system determines and controls blower speed, outlet air temperature, and outlet selection. The automatic climate control system also permits manual selection of temperature and air distribution if desired. A A/C Control Unit contains an electronic processor which receives inputs from sensors and provides outputs to control actuators. Sensor input information includes outlet air temperature and passenger compartment air temperature. The passenger compartment air temperature value is compared with the passenger-selected value. If the two values are different, the A/C Control Unit commands electric servo motors to move air distribution flaps to change the outlet air temperature. The A/C Control Unit communicates with the DME. It is the DME that actually commands the A/C compressor clutch ON and OFF. The instrument cluster communicates with the A/C Control Unit by means of a serial interface (2000 and earlier) or Bus (2001 on). Page 3.8 Climate Control Systems Diagnosis & Repair

43 Sports Cars System 1 (9x6) The instrument cluster provides the following information to the A/C Control Unit: Notes: Ambient temperature (from the sensor at the right front) Engine coolant temperature Engine rpm Vehicle speed Parked time since ignition OFF When the A/C system is in the automatic mode, the processor calculates the Energy Requirement Level (ERL) to determine the thermal energy requirements. All control functions depend upon the ERL value. The ERL is derived from: Passenger compartment actual temperature Passenger compartment desired temperature Ambient temperature Solar energy level A/C ON-OFF status Climate Control Systems Diagnosis & Repair Page 3.9

44 Sports Cars System 1 (9x6) Sensors and Actuators Boxster (986) & 911 (996) Through MY 2000 Page 3.10 Climate Control Systems Diagnosis & Repair

45 Sports Cars System 1 (9x6) Sensors and Actuators Sports Cars MY on * * For 2005 the A/C pressure switch was changed by connecting directly to the A/C controller line inputs and outputs for infinite radiator fan control. Climate Control Systems Diagnosis & Repair Page 3.11

46 Sports Cars System 1 (9x6) Sensors Refrigerant pressure is monitored to prevent A/C system operation when pressures are very low or high. High refrigerant pressure also signals increased condenser fan speed for additional airflow and cooling. 3-Way Refrigerant Pressure Switch (High/Low and Medium Pressure Switch) The 3-way refrigerant pressure switch (high/low and medium pressure switch) has two switches in one unit. The first switch is a high/low pressure switch in the compressor clutch circuit. The switch is normally closed, and the contacts will open when refrigerant pressure exceeds very high or low thresholds. As long as refrigerant pressure is typically between 2-26 bar ( psi), the switch contacts will remain closed. When the high/low pressure switch contacts open, this opens the power circuit to the A/C compressor relay. The switch contacts will again close when pressures are typically between bar ( psi). The second switch is the medium pressure switch. This is a normally-open switch, and the switch contacts will close when refrigerant pressure typically exceeds 16 bar (232 psi). The medium pressure switch is in the DME circuit to control the condenser fan. The DME control unit runs the condenser fan at second speed when the switch contacts close. This high fan speed moves more air through the condenser and reduces high side refrigerant pressure. The 3-way pressure switch is installed in the system high side near the expansion valve. Fresh Air Intake Temperature Sensor The fresh air intake temperature sensor supplies a signal for outside temperature to the A/C Control Unit. The sensor is mounted in the air distribution housing on the right side. It is in the fresh air intake near the recirculation flap. The A/C Control Unit compares the values from both the ambient temperature sensor and the fresh air intake sensor and uses the lower of the two inputs for the ambient temperature value. Ambient Temperature Sensor The ambient temperature sensor supplies an analog signal for outside air temperature to the A/C Control Unit. The sensor is mounted in the front of the vehicle on the right side. Page 3.12 Climate Control Systems Diagnosis & Repair

47 Sports Cars System 1 (9x6) Interior Temperature Sensor Solar Sensor The interior temperature sensor sends a signal to the A/C Control Unit for interior temperature. Interior temperature is sensed and compared with the target temperature requested by the passengers, and also ambient temperatures. This comparison influences outlet temperatures and blower speed. The control unit will command a higher blower speed or temperature flap position if there is a large difference between the two temperatures. The sensor is located on the right side of the dash. The sensor is integral with the interior sensor blower. The blower draws the passenger compartment air past the sensor for improved accuracy. Solar intensity is detected by photo diodes in the solar sensor. The signal from the solar sensor is used along with temperature measurements to improve the A/C system s ability to accurately judge the expected heat load. An increase in sensed solar radiation causes the A/C Control Unit to command an increase in blower speed. Changes in solar intensity register after a delay of typically 3-8 seconds. This prevents unnecessary adjustments by the automatic A/C system in response to transient conditions. The solar sensor is located on the top of the dash in the center. Footwell Outlet Temperature Sensor The footwell outlet temperature sensor sends a signal to the A/C Control Unit for footwell outlet air temperature. The sensor is located on the lower left side of the air distribution housing. Notes: Climate Control Systems Diagnosis & Repair Page 3.13

48 Sports Cars System 1 (9x6) Air Control Flap Position Sensors Cooling Fans Automatic Climate Control system air control flap motors have feedback position sensors built-in. The position sensor is a potentiometer which provides an analog signal to the A/C Control Unit for flap position. There are four air control flap position sensors in Boxster (986) & 911 (996) air distribution housings: Fresh air/recirculation flap position sensor Footwell/defrost flap position sensor Temperature flap position sensor Central flap position sensor Actuators Compressor Clutch The cooling fans promote airflow through the engine coolant radiators and condensers to improve heat transfer from the refrigerant to ambient air. A ballast resistor (see graphic) reduces voltage to the condenser fans for first (low) speed operation. The resistor is bypassed and the condenser fans will run at second (high) speed when refrigerant pressure exceeds 16 bar (232 psi). This is controlled by the 3-way medium pressure switch via the DME. The cooling fans will run at second (high) speed when engine coolant temperature exceeds 102 C (216 F). Air Control Flap Motors An electromagnetic clutch engages and drives the compressor. The clutch hub and spring plate are attached to the compressor shaft and turn with it. The clutch pulley is driven by the serpentine accessory belt. When the electromagnetic clutch coil is energized, the spring plate and hub are attracted to the pulley by a strong magnetic field and they both rotate together. The DME controls compressor clutch engagement. The A/C Control Unit also receives a signal and knows the clutch status. The clutch can be removed and replaced separately. Air control flaps in the air distribution housing are moved by air control flap motors. These are electric motors that are moved on commands from the A/C Control Unit. Page 3.14 Climate Control Systems Diagnosis & Repair

49 Sports Cars System 1 (9x6) There are four air control flap position sensors in Boxster (986) & 911 (996) air distribution housings: Fresh air/recirculation flap position sensor Footwell/defrost flap position sensor Temperature flap position sensor Central flap position sensor Blower voltage also increases with increased solar load to compensate for the increased solar radiation. When manual air recirculation is selected, blower voltage is reduced to 85% to reduce noise. Blower Regulator Fresh Air Blower The fresh air blower moves air through the air distribution housing. Blower speed is controlled by the blower regulator. The A/C Control Unit outputs an analog signal to the blower regulator to set the appropriate blower speed. The blower regulator is located on the air distribution housing on the right side near the blower. A heat-sink on the back side of the blower regulator is placed in the housing airstream to prevent overheating of the module. Do not operate the blower with the blower regulator out of the airstream or with the vehicle fresh air inlet blocked. During a cold start, the voltage to the fresh air blower is reduced by 50% to prevent the unpleasant discharge of cold air. At ambient temperatures < -10 C (14 F), blower speed is increased to improve heating. The blower regulator (blower final stage) sets the desired blower speed. The blower regulator is controlled by an analog signal for blower speed from the A/C Control Unit. The blower regulator is attached to the air distribution housing and has a heat-sink which dissipates heat in the blower airstream. Do not operate the blower unless the regulator is bolted in position. Manual Blower Control Blower speed can be manually set with the + and - blower buttons. The blower can be turned off by repeatedly depressing the - button until OFF appears in the display. If the blower is turned OFF while A/C is ON, the compressor clutch circuit will open to prevent evaporator icing. In the blower-off mode, air distribution is set to defrost and air recirculation is cancelled. Notes: Climate Control Systems Diagnosis & Repair Page 3.15

50 Sports Cars System 1 (9x6) Service and Diagnosis Information Climate Control Unit Diagnosis When the A/C system is in the automatic mode, the A/C Control Unit monitors heat load requirements by means of a calculation called the Energy Requirement Level (ERL). All control functions depend upon the ERL value. The ERL variable is derived from: Through MY 2000, the A/C Control Unit communicates with the PIWIS Tester through the K data line. From MY 2001, the control unit communicates via low speed comfort CAN to the cluster, which then communicates via high speed CAN to the DME. The A/C Control Unit outputs a pulse width modulated (PWM) signal to the DME control unit. The signal indicates the load that the climate control compressor is placing on the engine so that the DME can compensate. Passenger compartment actual temperature Passenger compartment desired temperature Ambient temperature Solar energy level A/C ON-OFF status Blower Control The A/C Control Unit regulates voltage to the blower when in the automatic mode. The following conditions affect blower voltage: The ERL value is between 0-255, with 0 = max. cooling and 255 = max. heating. The A/C function is ON with ERL values < 85, and the heating function is ON with ERL values > 150. The chart below shows temperature mixing flap position vs ERL. Cold Start Blower voltage is reduced by 50% during a cold start. This prevents the unpleasant discharge of cold air. Low Ambient Correction At ambient temperatures below -10 C (14 F), blower voltage and speed is increased to increase heating. Solar Radiation Correction A radiation-dependent correction in blower voltage compensates for increased heat load from solar radiation. Recirculation Mode Correction Blower speed is reduced during manual recirculation to reduce noise. Blower OFF Mode When the blower is turned OFF manually, air distribution is set to defrost and recirculate. See the chart below for blower voltage values. Climate Control Unit Communications Heating-A/C Control Unit communicates with the PIWIS Tester through the K data line. Heating-A/C Control Unit outputs a pulse width modulated (PWM) signal to the DME control unit. The signal is a load indicator so that the DME can compensate engine idle speed. The signal period is 280 ms and the pulse width steps in 40 ms increments. The duty cycle is 100% with an ERL value < 30, indicating max. cooling. The duty cycle is 0% when the A/C compressor is turned OFF (in Economy mode, for example). Page 3.16 Climate Control Systems Diagnosis & Repair

51 Sports Cars System 1 (9x6) Evaporator Moisture condensing on the cold evaporator fins drains out the bottom of the air distribution housing. Be sure that this drain does not become obstructed or plugged. Water coming from outlets at high blower fan speeds can indicate drain blockage. Evaporator fin temperatures cannot be allowed to drop below the freezing point of water. If this happens, the evaporator can become blocked with ice and airflow can be reduced. Evaporator temperature is maintained by varying compressor displacement. This controls the amount of refrigerant pumped through the system and refrigerant pressure and temperature in the evaporator. These systems are very tolerant of faults and can be difficult to diagnose. On Board Diagnostics The A/C Control Unit monitors its own function and also various sensors and actuators. If a fault is detected, a fault code is stored in non-volatile memory (EEPROM). Sensor circuits are checked for signal plausibility and also whether the signal is within range. If a sensor circuit fault is detected, the system ignores the signal and substitutes a stored default value. In this way, emergency operation of the climate control system can be maintained. See the chart below for sensor default values. Fault Memory The following parameters are monitored and will set fault codes if defects are found: Interface with the instrument cluster Outside temperature sensor Interior temperature sensor Blower outlet sensor Supply Voltage (terminal 15) Supply Voltage (5 V) Air control flap motors A/C compressor demand Fresh air blower Control unit fault Solar sensor When a fault is detected, the fault counter is set to 50. For each trip during which the diagnostics do not detect the fault, the fault counter is decreased by 1. When the fault counter reaches 0, the fault is erased from the memory. Climate Control Unit The A/C Control Unit has four connectors in the rear. From MY 2001, units use connectors B and D only. See the Workshop Manual for pin assignments and also procedures for other circuit tests. See the illustration below for connector locations. Climate Control Systems Diagnosis & Repair Page 3.17

52 Sports Cars System 2 (9x7) Sports Cars 9x7 A/C System Description 911 Carrera (997) MY 2005 to 2008 (including GT3) 911 Turbo (997) MY 2007 to 2009 (including GT2) Boxster/Cayman (987) MY The next evolution of the sports cars A/C system appeared on MY (997) models. The basic system shared many of the original design elements from the 9x6 models and was used through MY 2008 (911 Turbo (997) through MY 2009). Center Air Outlet Vent Shut-off Flaps The increased vertical and horizontal adjustment range of the vents and the separate left/right knurled wheel for the center vent permit more specific adjustment of the air flow than was previously possible. The vents should be closed when a high level of heating is required and opened when a high level of cooling is necessary. Air Conditioning, Manual Air Conditioning Boxster/Cayman (987) - Standard Equipment ECO marking (ECOnomy mode) on the button for switching the air conditioning compressor on and off (snowflake symbol on display goes on /off accordingly). As a result of these changes, all of the heating functions in the vehicle are now together in a single unit. The following items of information can be called up on the air conditioning display: Temperature and air flow rate (fan speed) A/C compressor on/off AC max mode Air distribution The temperature is presented on the display by way of a bar display. When no bar is visible, the temperature is set to the maximum cold setting (low) When all the bars are visible, the temperature is set to the maximum warm setting (high) Control Panel (Manual A/C) Functions This air conditioning system, which enables continuous adjustment and setting of the desired cooling power and air flow rate (fan speed) via rocker switches according to individual wishes, controls the temperature of the conditioned air mixture by mixing warm and cold air in the heater box. Operation (manual air conditioning system) The air conditioning system is operated by way of a control panel (a/c controls) with integrated control unit in the center console. The appearance of the control panel for the manual air conditioning system is based on that of the control panel for the automatic climate control system. The key features of the control panel are: Integration of the interior temperature sensor (required for the seat heating functions) Integration of the switches for heating the driver s and passenger s seats (previously in the center console) Integration of the button for heating the rear window (previously located beside the operating unit) Introduction of switches for adjusting the temperature and fan power (higher setting = switch up, lower setting = switch down) A - Seat heating (left / right) B - Defrost windshield C - Recirculating air D - Interior temperature sensor is motor ventilated (behind the slotted cover) and is only used to stop seat heating when temperature gets above 104 F. (40 C) E - ECObutton (ECOnomy mode), the compressor is switched off via a relay at the touch of a button F - Defrost rear window G - Temperature setting H - AC max mode I - Button for air distribution in the footwell J - Button for air distribution to the air outlet vents (central and side vents) K - Button for air distribution in the direction of the windshield L - Air flow rate adjustment (fan speed) Page 3.18 Climate Control Systems Diagnosis & Repair

53 Sports Cars System 2 (9x7) E - ECO Button (air-conditioning compressor off/on) Notes: The ECO button enables the selection of ECOnomy mode, which functions without the a/c compressor. ECOnomy mode permits cooling to values down to the exterior temperature. H - AC Max Mode This button can be pressed in any other operating mode to cool the vehicle s interior as quickly as possible. The temperature display indicates the lowest value and the fan is activated at maximum speed Distribution flap for fresh air/recirculated air is closed Air flow is directed to the defrost air outlet vents (front windshield) and the central and side vents Other button functions on the control panel are explained in the section on Automatic climate control Note! Back Pressure Compensation was not used in Boxster/Cayman (987) manual A/C System). Climate Control Systems Diagnosis & Repair Page 3.19

54 Sports Cars System 2 (9x7) Air Conditioning - Automatic Climate Control 911 Carrera/S (997) - Standard Equipment Boxster/Cayman (987) - Optional Equipment Operation (automatic climate control panel) Functions This air conditioning system controls the interior temperature preselected on the control panel completely automatically. The desired interior temperature can be set between 61 F. (16 C) and 85 F. (29.5 C). It is generally recommended to set the interior temperature to approx. 72 F. (22 C). The system detects operating and ambient conditions of relevance to the interior climate via sensors and CAN. Automatic control is carried out primarily by way of the interior temperature sensor, the exterior temperature sensor and the solar radiation energy as detected by a sun sensor. This information is processed in the control unit (control panel) and converted into output signals for temperature control, the air distribution flaps (temperature and air distribution flaps are DC drive motors with position feedback), the fan and the compressor. In addition to automatic climate control, the control panel also enables manual selection of the desired system status at any time. Changes regarding: temperature air flow rate air distribution can be carried out by way of the control panel. The cooling output of the air conditioning system is generated by a volume controlled swash plate (adjustable) compressor. Demand dependent metering of the refrigerant delivery rate helps to save energy, while continuous power consumption of the compressor helps to optimize idle speed. A - Seat heating (left / right) The air conditioning system is operated by way of a A/C Control Unit with integrated control unit in the center console. The control panel differs visually from that on the previous Boxster (986) models because of the addition of a new control interface. The main changes to the control panel are: Integration of the interior temperature sensors (previously in the dashboard on the passenger s side) Integration of the switches for heating the driver s and passenger s seats (previously in the center console). Integration of the button for heating the rear window (previously located beside the operating unit) Introduction of switches for adjusting the temperature and fan power (higher setting = switch up, lower setting = switch down). ECO marking (ECOnomy mode) on the button for switching the air conditioning compressor on and off (snowflake symbol on display goes on /off accordingly). As a result of these changes, all of the heating functions in the vehicle are now together in a single unit. Control Panel Information is displayed by means of an LCD display and signalling lights (LEDs) in some buttons. When LO or HI appear on the display of the a/c control unit, this indicates that the system is operating at maximum cooling or heating power (the temperature control function is deactivated). LO and HI are displayed by the nominal temperature value segments. OFF on the display indicates that the fan is off. Page 3.20 Climate Control Systems Diagnosis & Repair

55 Sports Cars System 2 (9x7) A - Seat Heating on/off The seat heating settings can be adjusted individually for the left (button A) and right (button G) side. Apart from OFF level, two heating levels can be selected. When the appropriate button is pressed, the air conditioning control unit (control panel) transmits the altered button status (pressed 1x or 2x) to the vehicle electrical system control unit. The vehicle electrical system control unit controls the heating elements in the seat directly (heating-up phase) and reports the relevant heat status (setting 2 or setting 1) back to the control panel. This heating status is indicated to the user via the LED in the seat heating button. The operating time during the heating up phase is based on the interior temperature (CAN signal) according to the selected heat setting: Level 2 (at 104 F. (40 C) to <-4 F. (-20 C) from 2.2 to a maximum of 11.0 minutes Level 1 (at 104 F. (40 C) to <-4 F. (-20 C) heats from 0.5 to a maximum of 9.2 minutes After the heating up phase the control unit switches to the continuous heating phase. The vehicle electrical system control unit now reduces the heating power of level 2 to 40 % and level 1 to 14 %. B - Windshield The defrost function can be activated immediately in all operating modes. On activation of this function, the temperature is switched to HI, the air flow rate is increased and the air is distributed primarily towards the windscreen. ECO mode is additionally ended, if the intake temperature conditions (fresh air intake temperature sensor >37 F. (3 C) permits. If the compressor cannot be activated, recirculation air mode will be started. C - Recirculation Mode 2 Mode of functioning of automatic recirculation mode At exterior temperatures of >79 F. (26 C), recirculation mode is selected automatically by the program after a ventilation time of 30 seconds in order to accelerate the cooling-down phase - with the air conditioning switched on. E - ECO Button (air conditioning compressor off/on) The ECO button enables the selection of ECOnomy mode, which functions without the a/c compressor. ECOnomy mode permits cooling to values down to the exterior temperature. F - Defrost Rear Window/Door Mirrors The heated rear window button in the control panel generates an electrical impulse, which is sent to the vehicle electrical system control unit via CAN. Once the vehicle electrical system control unit has activated the heated rear window relay (in relay holder 2), it sends the switch on status of the heated rear window back to the air conditioning control panel. The LED in the button on the control panel is then activated. The ON status of the heated rear window on the CAN bus causes the two door control units (in parallel with the window heating) to directly control the heating elements for the defrost function of the door mirrors. The maximum heating time for the rear window and door mirrors is 15 minutes. I - Automatic Mode Air distribution is controlled automatically. In addition to the state variable Energy Requirement Level (see section Actuators and sensors ), the program also evaluates the outside temperature and engine temperature in order to take due account of cold start conditions and possible icing of the windows. Automatic mode is confirmed by the word AUTO on the display. 1 Mode of functioning of manual recirculation mode The fresh/recirculated air distributor flap can be activated at any time to prevent odour nuisance. However, recirculation mode is limited to max. 3 minutes when the air conditioning compressor is switched off (ECOnomy mode). Climate Control Systems Diagnosis & Repair Page 3.21

56 Sports Cars System 2 (9x7) M - Manual Fan Adjustment In addition to automatic control, the fan output can also be adjusted manually by way of the rocker switches. The current air flow rate is indicated by a 19-bar indicator on the display. The pressure sensor is installed in the system high side near the expansion valve. Pressing the rocker switch up increases the fan output. Pressing the rocker switch down reduces the fan output down to a minimum of zero bars on the display. After releasing the switch and then pressing it down again, the fan is switched off (OFF mode). OFF appears on the display. When the fan is switched off, a compressor shutdown function protects the evaporator from icing. In fan OFF mode, air distribution is set to defrost (defrost/footwell distributor flap) and recirculation (fresh/recirc. air distributor flap) and all other actuators are shut down. Pressure Sensor The pressure sensor is an essential instrument in assessing the air conditioning system. It detects the current pressure in the system and supplies a PWM signal (PulseWidthModulation) to the a/c control unit. The A/C Control Unit relays this signal to the CAN bus for further use. This PWM signal is employed for the purposes of: Low-pressure shut-down (p < 29 psi/2 bar) High-pressure shut-down (p > 406 psi/28 bar) Condenser cooling (see also section Condenser fan ) The following components serve as actuators: 1 - Expansion valve 2 - Service connection suction side 3 - Service connection pressure side 4 - Air conditioning system pressure sensor (located on the highpressure side of the cooling circuit) Interior Temperature Sensor The interior temperature sensor is integrated into the middle of the A/C Control Unit (behind the slotted cover) ensures that the automatic air conditioning control system responds to temperature changes with a substantially greater degree of precision. In order to avoid measuring errors resulting from heating-up of the control panel area, the interior air is extracted over the sensor by way of a micro fan. Cooling Fans The engine coolant radiator and condenser fan speed is controlled by the DME and fan speed is infinitely variable. Inputs are received by the DME for refrigerant pressure (supplied via CAN from the A/C control unit) and engine coolant temperature. The DME sends the fan speed command via CAN Drive to the gateway and via CAN Comfort to the front-end control unit. Drive motor for temperature mix flap Drive motor for central distributor flap Drive motor for defrost/footwell distributor flap Drive motor for fresh air/recirc. air distributor flap PWM - fan motor voltage Page 3.22 Climate Control Systems Diagnosis & Repair

57 Sports Cars System 2 (9x7) The front-end control unit controls the cooling fans (right and left) together via a pulse width-modulated (PWM) signal to an output module. The output module evaluates and processes the PWM signal and relays it to the fans. Notes: Refrigerant Pressure vs. Fan Speed in Percent Coolant Temperature vs. Fan Speed in Percent Climate Control Systems Diagnosis & Repair Page 3.23

58 Sports Cars System 2 (9x7) Service and Diagnosis Information Service and diagnosis is similar to the 9x6 system. The following is for the 9x7 series (Except Boxster/Cayman (987) w/manual A/C). Information Transmitted via the CAN Interface Sports Cars MY on The system communicates the following climate relevant operating and ambient conditions via the CAN interface: Outside temperature (via CAN from the front end control unit) Coolant temperature Vehicle speed (to assess the fresh air intake temperature) Engine speed Request Defrost rear windshield/door mirrors (status on/off via CAN on the vehicle electrical system control unit) Cabriolet top open/closed Sun sensor Dimming (from instrument cluster) Wipe/wash signal Request Seat heating left (status: on/off via CAN on the vehicle electrical system control unit) Request Seat heating right (status: on/off via CAN on the vehicle electrical system control unit) Interior temperature (actual temperature via CAN to vehicle electrical system control unit) Request - a/c compressor (status on/off via CAN on the DME engine control unit) Pressure signal (indirect request for condenser cooling through provision of coolant pressure via CAN) A/C shutdown (e.g. high and low pressure shutdown) Diagnosis Stationary period since ignition off (from instrument cluster) Steering angle sensor - If control module detects lots of steering angle changes it drops the temperature a little without changing the driver s selection (for comfort of driver) Diagnosis Diagnosis with the PIWIS Tester is carried out via the CAN interface (diagnosis socket). Further key functions are available via the diagnosis interface: Readout and erasure of fault memory Output of measurement and operating data (e.g. actual values) Actuator control Coding Calibration processes Fault Detection The system incorporates a self-diagnosis facility which continuously monitors certain functions of the control unit or system components and records faults in a non volatile fault memory (EEPROM). Sensor Default Values As on the previous 9x6 series, in the event of a short-circuit or interruption of a sensor default values are employed to maintain operation of the a/c control system in emergency mode. Parameter Possible Fault Location Default Values Outside temperature Sensor/front-end control unit 50 F. (10 C.) Interior temperature Sensor/air con. control panel 72 F. (22 C.) Footwell temperature Sensor 122 F. (50 C.) Engine temperature Sensor/engine control unit 176 F. (80 C.) Sun intensitysensor 150 W/m 2 Speed Sensor/PSM 43 mph (70 km/h) Engine speed Sensor/engine control unit 1000 rpm Page 3.24 Climate Control Systems Diagnosis & Repair

59 Sports Cars System 3 (9x7) Sports Cars 9x7 A/C System Description 911 Carrera/S (997) MY 2009 Boxster/Cayman (987) MY 2009 Externally Controlled Compressor Beginning with MY Carrera (997) & Boxster/ Cayman (987) (2nd generation) the system uses an externally controlled compressor. With an externally controlled system, the air conditioning operating panel has a direct effect on the compressor and thus on the cooling output. Given this, most changes here relate to the compressor or compressor control. The components, which you will be familiar with from the air-conditioning system used in the previous model, are not modified to any great extent by this system and are essentially identical from the point of view of design and operating principle. A comparable externally controlled compressor system is also used in the Cayenne. Advantages of an externally controlled compressor: Reduced weight due to removal of a compressor clutch Total weight loss here: approx. 3 lbs. (1.4 kg) No need to push the clutch when engaging (highcomfort use) Refrigerant output is controlled more precisely and is demand-controlled, based directly on the evaporator temperature System parameters Externally controlled compressor (electronic control valve) No magnetic clutch (compressor runs continuously) System is controlled via evaporator temperature (similar to the Cayenne) Control valve is activated from the air conditioner operating panel (new software) Some refrigerant lines are re-routed due to modified engine (DFI engine) Operating principle of the externally controlled compressor The externally controlled compressor (from Denso) is an air side-controlled swash-plate (adjusting) compressor, similar in function and design to the compressors used in the previous models. The gaseous refrigerant has a pressure of 145 to 435 psi (10 30 bar) and a temperature of up to 212 F. (100 C.) when it exits the compressor at a maximum delivery rate. The compressor continues to run at the existing engine speed and is not just switched on via a clutch relay. An electronic control valve integrated in the compressor also allows the high pressure of the refrigerant circuit of approx. 145 to 435 psi (10 30 bar) into the crank chamber housing if necessary (a by-pass bore opens). Like all similar compressors, the crank chamber is connected to the low-pressure side of the refrigerant circuit via another bore for the return (pressure compensation between the high and low-pressure side via the return bore). As a result, the angle of attack of the swash plate can be reduced (towards zero delivery) without any great force by a spring working on the plate. The control valve is controlled by a variable PWM signal from the air conditioning control unit (operating panel). The control unit uses the signal from an evaporator temperature sensor as the basis for controlling the control valve (for more information, see Evaporator temperature sensor ). The basic frequency for the valve is 400 Hz. Note! The air-conditioning compressor switches off automatically at outside temperatures of below approx. 35 F. (2 C.) and cannot be switched on again even manually by pressing the Auto button. The pressure relief valve opens at a critical system pressure of 2030 psi (140 bar) to protect the lines from irreparable damage. The valve closes again when pressure compensation is complete. The valve is located directly on the compressor, on the high-pressure side. Climate Control Systems Diagnosis & Repair Page 3.25

60 Sports Cars System 3 (9x7) Variable PWM Signal (400 Hz) Operation (air conditioning operating panel) Amperage rating [amp] Compressor status 0,0 0,3 Off (no load) 0,3 0,8 Continuous adjustment > 0,8 Limited The piston stroke as described above under pressure compensation in the crank chamber housing can be varied continuously by changing the amperage rating of the PWM signal (opening a by-pass bore). This type of control ensures a large stroke for a high (refrigerant) delivery rate and a small stroke for a lower delivery rate from the compressor. Since the compressor operates with a variable delivery rate, there is no need to control the cooling output of the air conditioning system by switching a compressor relay on and off. In other words: the compressor continues to run even when there is sufficient cooling output, but can operate with zero delivery (swash-plate deflection: approx. 3 degrees). In this case, the compressor is running without a load. Note! At a coolant temperature of T > 244 F. (118 C.), a forced suppression of the air conditioning system is requested of the air conditioning control unit by the DME system via the CAN bus. For this purpose, the electronic control valve sets the compressor to zero delivery mode (both radiator fans running). Note! Air conditioning control is operated via an operating panel (air-conditioning regulator) with an integrated control unit in the center console. The operating panel looks similar to the operating panel used in the current sports car except for small changes on the operator interface. These changes are not relevant for the externally controlled compressor. The most important changes on the operator interface are as follows: AC OFF (ECO function = compressor runs in zero delivery mode) Integration of the two buttons for air-conditioned seats (see also system description for Air-conditioned seats ) Position of some operating buttons changed As on the previous model, all heating functions in the vehicle are controlled via one unit. Note! Information is provided via CAN in order to dim the displays in the LCD display. A timed full-load shutdown (compressor function is disabled) occurs if the throttle position is greater than 92%. Speed is taken into consideration here when setting the driver setpoint torque. Notes: Page 3.26 Climate Control Systems Diagnosis & Repair

61 Sports Cars System 3 (9x7) Evaporator Temperature Sensor Heat and/or Ventilated Seats The temperature of the evaporator is primarily used as the basis for controlling the electronic control valve in the externally controlled compressor. The sensor is not fitted directly in the evaporator vanes. It is located at a parallel position approx. 20 mm behind the evaporator. At this distance from the evaporator, the sensor can measure a homogenous air-flow temperature for all temperature levels. The evaporator is also prevented from freezing, based on this measured temperature. If there is a danger of freezing, the air conditioning operating panel reduces the angle of attack of the swash plate (pressure compensation between high and low-pressure side) by triggering the electronic control valve and thus reduces the refrigerant delivery rate. There is now less refrigerant available for evaporation and this counteracts the possibility of freezing. Position of the Evaporator Temperature Sensor General Information Seat ventilation or ventilation for the two front seats (standard or fully electric seats) is available as an option for the first time in conjunction with heated seats for the new 911 (997) & Boxster/Cayman (987) (2nd generation) models. Three comfort settings can be activated independently using buttons in the air conditioner operating panel. The fans integrated in the seat and in the backrest remove perspiration between the passenger and the surface of the seat. This ensures that passengers enjoy pleasant and dry seating comfort without drafts, even in extreme heat. Advantages of ventilated seats: On the sports car, the evaporator temperature sensor (arrow) is located on the back of the heater unit housing. The connecting cable for the sensor is routed close to the condensation outlet. To remove this sensor, you must reach in between the bulkhead (passenger s side) and the rear wall of the housing. The sensor is released when it is turned a quarter-turn and can then be removed from the heater unit housing. Healthy and warm/dry air conditioning on the seat surface Improved passenger comfort by regulating the transport of heat/moisture Increased personal comfort Excellent seating comfort Climate Control Systems Diagnosis & Repair Page 3.27

62 Sports Cars System 3 (9x7) Note! A temperature sensor is integrated in the heating element in the seat surfaces of both seats. A temperature of at least 59 F. (15 C.) must be measured both by the temperature sensors in the seats and the interior temperature sensor (in the operating panel). Seat airing and ventilation is not switched on or off if the temperature is less than 59 F. (15 C.) in order to prevent supercooling. Operating Principle of Ventilated Seats Fine perforations in the leather cover on the center strip of the seat and backrest allow the surface ventilation or airing of the seat upholstery. The passengers' requirements with regard to seating comfort for the two front seats can be met individually by adjusting the ventilation and air-conditioning level and selecting the required seat heating setting. Seat ventilation/airing can be switched on and off at the touch of a button on the air conditioner operating panel. The highest of the three comfort settings is activated first when you touch the button. The three LEDs in the switch show which ventilator setting is currently activated. The fans are powered directly by the vehicle electrical system (terminal 15). Seat ventilation and seat heating only works when the engine is running. The decision as to whether both systems (seat ventilation and seat heating) are activated depends on the air conditioner operating panel. Components of Ventilated Seats The system, which can be ordered as an option together with seat heating, comprises the following main components: 3-stage operating button in the air conditioner operating panel next to the operating button for seat heating for driver and passenger Fan modules for the seat surface (item 1) and backrest (item 2) Air ducts in the seat surface and backrest (see arrows for air routing) Air-permeable cushioned mats Main wiring harness (not described here) The seat surface is ventilated evenly by a fan controlled by the air conditioner operating panel and integrated in both the seat and backrest. The efficient and acoustically discrete fans draw off perspiration between the passenger and the surface of the seat through the perforated center strip in the seat and backrest. The intake air flows through an air-permeable cushioned mat, is transported off via special air ducts arranged in the seat and is directed into the interior of the vehicle. In this way, the seat surfaces heated by the sun cool down quickly and prevent perspiration. Seat ventilation can be combined with seat-heating temperature control. This ensures the continuous removal of moisture while maintaining a pleasant seat-surface temperature. Controlling Ventilated Seats The fan modules in the seat surfaces and backrests are activated directly from the air conditioner operating panel. The PWM signal used for this has a frequency of 100 Hz. The three possible settings run at 100%, 78% and 68%. Note! The fans are no longer activated or switched off automatically by the air conditioner operating panel when the voltage is less than 9 volts and more than 16 volts. Page 3.28 Climate Control Systems Diagnosis & Repair

63 Sports Cars System 3 (9x7) The signal from the temperature sensor (sensor integrated in the seat-surface heating element) is used to regulate seat heating. Fan Modules for the Seat Surface and Backrest 2 2 Air-Permeable Cushioned Mats Filter module 2 - Cushion foam 3 - Air-permeable cushioned mat Air Ducts for the Seat Surface and Backrest Air-permeable cushioned mat 7 - Heating element (integrated temperature sensor) 8 - Cushion foam 9 - Fan module carrier 10 - Fan module 11 - Seat spring 4 - Cushion foam structure (fixed in the middle) 5 - Opening for fan module (seat surface) Climate Control Systems Diagnosis & Repair Page 3.29

64 Sports Cars System 3 (9x7) Steering Wheel Heating Option Notes: General Information On sports cars, the sports steering wheel for PDK as well as the multi-function steering wheels for PDK, which are available on request, can come with steering wheel heating as an option for greater comfort during the cold season. Operating Principle Steering wheel heating can be switched on and off using a button on the 6 o'clock spoke of the steering wheel. When steering wheel heating is activated, the message Steering wheel heating ON appears for approx. 2 seconds on the on-board computer in the instrument cluster. The interior temperature sensor in the automatic air-conditioning operating panel is used as the basis for controlling steering wheel heating. The heating time is temperature-controlled via a variable timer. When this system is deactivated, the message Steering wheel heating OFF appears briefly on the on-board computer. Page 3.30 Climate Control Systems Diagnosis & Repair

65 Cayenne Systems (E1) Subject Page Cayenne A/C Systems Compressors Refrigeration Circuits Air Distribution System Air Distribution Components Rear Heating and Cooling Unit Auxiliary Park Heater Manual A/C Operation Climate Control Operation, 2-Zone Climate Control Operation, 4-Zone Climate Control Unit, Sensors & Actuators - 2-Zone Climate Control Unit, Sensors & Actuators - 4-Zone Sensors Actuators Service and Diagnosis Information Climate Control Systems Diagnosis & Repair Page 4.1

66 Cayenne Systems (E1) Notes: Page 4.2 Climate Control Systems Diagnosis & Repair

67 Cayenne Systems (E1) Cayenne A/C System Description The Cayenne V6 has a heating system in conjunction with manual air conditioning for climate control of the passenger compartment, satisfying the highest demands in comfort. Air conditioning with 2-zone or 4-zone control, is available as a option. The Cayenne S and Cayenne Turbo have 2-zone air conditioning as standard equipment, with 4-zone being available as a option. Compressor, 2-Zone & 4-Zone The Cayenne is equipped with a swash plate (regulated) compressor controlled on the low side that is similar in function and design to a compressor in a sports car. The refrigerant has a pressure of psi (10-30 bar) after exiting the compressor and a temperature of about 212 F. (100 C). The compressor runs whenever there are RPMs. Compressor, Cayenne (V6) On the manual air conditioning, the air blending swashplate (adjustable) compressor, similar to the 2-zone air conditioning, is used. The swash plate is adjusted through an electronic control valve integrated in the compressor. The control valve is actuated by a variable PWM signal from the air conditioning control unit (control panel). The variation of the PWM signal is basically caused by the vaporizer temperature sensor. As the compressor works with a variable delivery rate and zero delivery (delivery rate dd5%) is theoretically possible, it is not necessary to control the air conditioning cooling output through the switching on and off of a compressor relay (the compressor always runs if the engine is running). Through an electronic control valve, integrated into the compressor, the intake pressure (low pressure side, about psi/1-3 bar) in the compressor housing has an effect on the swash plate. The control valve is triggered by a PWM signal from the control module of the climate control. The basis for the triggering of the control valve is taken from the signal of the evaporator temperature sensor. The basis frequency for the valve is 400 Hz. 1 - Plug connector (electronic control valve) 2 - Pressure relief valve 3 - Connector opening, low pressure side 4 - Electronic control valve The piston stroke can be continuously varied, a large stroke for large refrigerant capacity and a smaller stroke for smaller capacity. Because the compressor works with a variable capacity demand, there is no compressor relay. This means that the compressor is always turning but there is no output at the lowest portion of the compressor stroke. Climate Control Systems Diagnosis & Repair Page 4.3

68 Cayenne Systems (E1) Refrigeration Circuit, Cayenne (V6) The following illustration shows the refrigeration circuit of the Cayenne with manual air conditioning. Refrigeration Circuit, 2-Zone Climate Control The cold air circulation in the Cayenne is set up so that the compressor and the expansion valve are the classic separations between upper and lower pressure sides. The following sections/components are built in and shown in the direction of the cold air circulation: The following section/components are installed and listed in order of the refrigeration circuit: 1 - Adjustable air conditioning compressor (front of engine) 2 - Condenser (sandwich design with engine radiator) 3 - Mounting (pipe) for the drier cartridge (replaceable cartridge; integrated) 4 - Service connector (high pressure) 5 - Pressure sensor is on high-pressure side 6 - Expansion valve (supply flow) 7 - Expansion valve (return flow) 8 - Service connector (low pressure) 9 - Pressure damper (low pressure side just in front of compressor, near left wheel arch) 1 - Compressor (front side of the motor) 2 - Condenser (sandwich design with radiator) 3 - Receptacle (pipe) for the drying cartridge (replaceable cartridges, integrated on the right outside of the capacitor) 4 - Service connection (high pressure) 5 - Pressure sensor is on the high pressure side 6 - Expansion valve (flow) 7 - Evaporator (evaporator cannot be seen in diagram) 8 - Expansion Valve (return) 9 - Service connection (low pressure) 10 - Pressure damper (low pressure side right in front of the compressor near the left wheel housing) Page 4.4 Climate Control Systems Diagnosis & Repair

69 Cayenne Systems (E1) Additional Refrigeration Circuit, 4-Zone Climate Control Notes: 1 - Refrigerant lines for the rear evaporator 2 - Line for the heating circulation for the rear heat exchanger Climate Control Systems Diagnosis & Repair Page 4.5

70 Cayenne Systems (E1) Pressure Relief Valve Receiver/Dryer The receiver/dryer on Cayenne models is a replaceable cartridge that is integrated into the right side of the condenser. The cartridge can retain 6-12 grams of water and is serviceable. An access cover is on top of the condenser. The refrigerant must first be recovered before changing the cartridge. The pressure relief valve is a mechanical valve on the compressor. It will open and vent refrigerant if pressure exceeds bar ( psi). The valve will close when pressure drops to a safe value. Pressure Damper The pressure damper is an enlarged chamber on the refrigerant system low side. The damper reduces refrigerant pulses in the line and reduces noise. It is located near the compressor in front of the left front wheel. Evaporator The A/C evaporator is located in the air distribution housing. Evaporator removal requires removal and disassembly of the air distribution housing. The evaporator temperature sensor is located right behind the evaporator. Thermostatic Expansion Valve (TEV) Condenser The H-type block Thermostatic Expansion Valve (TEV) is located on the engine compartment rear bulkhead. Both refrigerant lines to the evaporator pass through the expansion valve. The A/C pressure sensor is located in the same area. The A/C condenser is integrated into the engine coolant radiator module at the front of the vehicle. It is mounted in front of the engine coolant radiator and fan. Page 4.6 Climate Control Systems Diagnosis & Repair

71 Cayenne Systems (E1) Service Connections With the manual and 2-Zone climate control system, the temperature and air volume for the driver and front passenger can be separately adjusted. Outlets are located in the instrument panel, the rear console, and floor vents under the front seats. Air Ducting, 4-Zone Cayenne model service connections are in front in the engine compartment on the left side. Air Distribution System The air distribution system controls air volume, temperature and direction within the passenger compartment. The system can add or remove heat from the cabin air and provide ventilation, heating, cooling and defrost functions. On Cayenne models, the air distribution housing contains the evaporator, a heater core containing hot engine coolant, blower fan, air control flaps and their actuators, and passages to various outlets in the vehicle. Air Ducting The optional 4-Zone automatic climate control system adds a rear heating/cooling unit. The rear heating/cooling unit includes a rear blower, heater core and evaporator, along with the hoses, ducts and necessary controls. When the vehicle is equipped with the 4-Zone system, air from the front air distribution housing feeds the front seat panel and side vents. Rear seat passengers receive airflow only from the rear heating/cooling unit. The rear unit supplies air to the vents in the rear console, B-pillar and floor vents under the front seats. The rear heating/cooling unit is located on the left side in the side wall behind the left rear wheel. Notes: Climate Control Systems Diagnosis & Repair Page 4.7

72 Cayenne Systems (E1) Air Distribution Components Rear Heating and Cooling Unit These components make up the Cayenne air distribution system: Air Distribution Housing Evaporator Heater Core Blower Air Control Flaps Climate Control Unit Four-zone Components (optional) Cayenne models with the optional 4-Zone system have a rear heating/cooling unit. The unit is located in the rear cargo area on the left side, behind the left rear wheel housing. This system provides each rear passenger with separate controls for temperature and air distribution. Notes: Particle Filter All Cayenne models have a charcoal particle filter integrated into the air distribution housing. The filter is located in front of the evaporator and can be removed for service from the passenger side footwell. Page 4.8 Climate Control Systems Diagnosis & Repair

73 Cayenne Systems (E1) Auxiliary Park Heater An electric circulation pump, non-return valve and 3/2 wayvalve can isolate the park heater from engine coolant. The park heater is operated and set from the front control panel of the A/C system. The park heater can operate in any ignition key position. There are three independent memory locations for programming start times. In ROW vehicles, the park heater can also be operated from the remote control unit. The antenna is integral with the diversity antenna system in the rear spoiler. Note: Some park heater features are not available on North American vehicles. Cayenne models can be equipped with an optional auxiliary park heater to provide interior heat independent of engine coolant temperature. Heat is available before the engine is warm or with the engine not running. Combustion of gasoline fuel within the park heater combustion chamber is the heat source. Climate Control Systems Diagnosis & Repair Page 4.9

74 Cayenne Systems (E1) Air Conditioning, Cayenne (V6) Manual A/C Operation All Cayenne Models have air conditioning that operates with the environmentally friendly refrigerant R134a. Manual air conditioning is used on the Cayennne. The structural design of the manual air conditioning is basically the same as the 2-zone air conditioning. Due to the requirements of manual air conditioning compared to the 2-zone unit, certain actuator motors are not required. Air conditioning with zone control is available as a option. Function Air flow (blower), air distribution and temperature can be set on the manual air conditioning control panel. The following individual settings can be displayed in the air conditioning display: Air flow (blower) Air distribution Temperature adjustment Time synchronous to PCM or instrument cluster Suppression of compressor function (ECON) Residual engine heat utilization Auxiliary heater function Notes: A - Front windshield defrost B - Rear window defrost C - Recirculated air D - Air conditioning display E - Air flow button (blower) F - Air distribution to windshield G-Air distribution to middle and side vents H - Air to footwell I - ECON button (air conditioning compressor on/off) J-REST button (residual engine heat) K-Temperature button Climate Control The following varieties of climate control are available: 2-Zone Climate Control Standard equipment on Cayenne S & Cayenne Turbo, optional on the Cayenne (V6) 4-Zone Climate Control Optional on all Cayennes Page 4.10 Climate Control Systems Diagnosis & Repair

75 Cayenne Systems (E1) 2-Zone Climate Control, Cayenne S/T Operation 4-Zone Climate Control (Optional) Operation A - Defost Front Windshield B - Defrost Rear Window C - Auto Button (Automatic Operation) D - Automatic Circulating Air, Circulating Air E - Temparature Sensor is ventilatedby a motor (behind the slits) F - Climate Control Display G - Button for Air Volume (fan), left side H - Button for Temperature, left side I - Air Distribution for Front Windshield K - Air Distribution for Middle and Side Vents L - Air Distribution for Floor N - ECON Button (Climate Compressor off/on) U - REST Button (residual heat from the motor used with vehicles with 2 zone climate control) R - Button for Temperature right side S - Air Volume Button, right side A - Defrost Front Windshield B - Defrost Rear Window C - Auto Button (automatic operation), REST Button (motor residual warmth for vehicles with 4 zone climate control) D - Automatic Circulating Air, Circulating Air E - Temperature Sensor is Ventilated by a Motor (behind the slits) F - Climate Control Display G - Button for Volume of Air (fan), left side H - Button for Temperature, left side I - Air Distribution for the Front Windshield K - Air Distribution for the Middle and left Vents L - Air Distribution for Floor, left side M - Setting for Additional Climate Control for Rear Passengers N - ECON Button (Climate Compressor off/on) O - Air Distribution to Front Windshield, right P - Air Distribution for Middle and right vents Q - Air Distribution to Floor, right side R - Button for Temperature, right side Climate Control Systems Diagnosis & Repair Page 4.11

76 Cayenne Systems (E1) Climate Control Unit The standard Cayenne automatic climate control system provides 2-zone control, while a 4-zone with front and rear control is optional. 2-Zone Both temperature and air volume can be independently set left and right. The system will maintain the set temperature as conditions change. The Climate Control Unit contains an electronic processor which receives inputs from sensors and provides outputs to control actuators. Sensor information includes outlet air temperature and passenger compartment air temperature. The passenger compartment air temperature value is compared with the passenger-selected value. If the two values are different, the Climate Control Unit commands electric servo motors to move air distribution flaps to change the outlet air temperature. The Climate Control Unit is located in the dash and has the manual passenger s controls. Depressing the Auto button switches the system to automatic operation. When ambient temperatures are < 2 C (36 F), the processor does not permit A/C compressor operation, even when the Auto button is depressed. After the vehicle is turned off, depressing the Rest button allows continued heating of the interior for up to 20 minutes. This function circulates hot coolant and operates the blower. 2-Zone Sensors & Actuators Page 4.12 Climate Control Systems Diagnosis & Repair

77 Cayenne Systems (E1) 4-Zone In addition to the front A/C system, an A/C system for the rear passenger area is available as an optional extra on all Cayenne models. This second A/C system operates independently of the front system. Here again, temperature, air volume (blower) and left / right air distribution (zones) are individually selectable. In conjunction with the automatic front 2-zone A/C system therefore, the interior climate can be controlled for a total of 4 individual zones. 4-Zone A/C System Front Climate Control Panel The settings for the 4 zones can be made on the front control panel. There is also a button on the front control panel for the two rear zones. The settings for the rear areas can be made after this button is pressed briefly. The rear zones can also be controlled from the rear seats on the rear control panel. 4-Zone A/C System Rear Climate Control Panel 4-Zone Sensors & Actuators, Front Climate Control Systems Diagnosis & Repair Page 4.13

78 Cayenne Systems (E1) 4-Zone Sensors & Actuators, Rear Page 4.14 Climate Control Systems Diagnosis & Repair

79 Cayenne Systems (E1) Sensors A/C Pressure Sensor Evaporator Temperature Sensor The evaporator temperature sensor measures air temperature after it passes through the evaporator fins. The evaporator temperature sensor is located right behind the evaporator. The control unit monitors this sensor to prevent condensation on the evaporator fins from freezing and blocking airflow. When the control unit detects evaporator temperature lower than desired, it commands the compressor to reduce displacement and pump less refrigerant. Cayenne models use a refrigerant pressure sensor instead of pressure switches. The sensor outputs a digital pulse width modulated (PWM) signal that varies with changes in refrigerant high side pressure. The signal is an input to the Climate Control Unit. The sensor provides more information to the control unit than would be provided by a switch because it senses pressure throughout the entire operating range, not just at high or low pressure extremes. An integrated circuit and a silicon crystal in the sensor receive a reference voltage. As refrigerant pressure is applied to the crystal, it deforms and its resistance changes. The integrated circuit converts this voltage to a PWM signal at a frequency of 50 hz. The Climate Control Unit uses this input to manage compressor displacement during normal operation and prevents A/C operation at pressure extremes. The pressure sensor is installed in the system high side near the expansion valve. The evaporator temperature sensor standard value is between 3-12 C (37-54 F). This is a calculated value which changes based on the desired interior temperature setting and ambient temperature. Ambient Temperature Sensor The ambient temperature sensor supplies an analog signal for outside air temperature to the Climate Control Unit. The system uses the signal from this sensor and the intake air temperature sensor to calculate outside air temperature. The sensor is mounted in the front of the vehicle near the front bumper. Intake Air Temperature Sensor The intake air temperature sensor supplies a signal for ambient temperature to the Climate Control Unit. The sensor is mounted in the air distribution housing fresh air intake. The Climate Control Unit compares the values from both the ambient temperature sensor and the intake air temperature sensor to calculate outside air temperature. Compressor operation is not permitted at ambient temperatures < 2 C (36 F). Notes: Climate Control Systems Diagnosis & Repair Page 4.15

80 Cayenne Systems (E1) Interior Temperature Sensor Air Quality Sensor The interior temperature sensor sends an analog signal to the Climate Control Unit for interior temperature. Interior temperature is sensed and compared with the target temperature requested by the passengers, and ambient temperatures. This comparison influences outlet temperatures and blower speed. The control unit will command a higher blower speed if there is a large difference between these temperatures. The sensor is located behind slits in the Climate Control Unit. An integral blower moves interior air past the interior temperature sensor for improved accuracy. The air quality sensor monitors ambient air pollution and sends a signal to the Climate Control Unit. The control unit will command the recirculation flap to close if the concentration of pollution is excessive. The air quality sensor reacts to oxides of nitrogen (NOx), Carbon Monoxide (CO) and Sulfur Dioxide (SO 2 ). The air quality sensor is in the fresh air inlet on the left side. Notes: Outlet Temperature Sensors Outlet air temperatures are sensed by four outlet temperature sensors. This permits the control unit to monitor outlet air temperatures on the left and right sides separately, and to maintain different temperature settings on the left and right sides. The sensors are: Floor outlet temperature sensors - left and right Middle/side outlet temperature sensors - left and right Models with the optional 4-Zone system have two additional outlet temperature sensors in the rear heating/cooling unit: Rear air duct temperature sensors - left and right Page 4.16 Climate Control Systems Diagnosis & Repair

81 Cayenne Systems (E1) Solar Sensor Air Control Flap Position Sensors Automatic Climate Control system air control flap motors have feedback position sensors built-in. Each position sensor is a potentiometer which provides an analog signal to the Climate Control Unit for flap position. 2-Zone Sensors There are 7 air control flap position sensors in the 2-Zone Cayenne air distribution housing: Solar intensity is detected by two photo diodes in the stereo solar sensor. The solar sensor is able to measure the sun s intensity separately from the left and right sides. The system reacts to changes in solar intensity after time delays of typically 50 seconds with increasing solar intensity and 200 seconds with decreasing solar intensity. This prevents unnecessary adjustments by the automatic A/C system in response to transient conditions. Fresh air/recirculation flap position sensor Defrost flap position sensors Middle vent position sensors Side vent position sensors Floor vent position sensors Temperature flap position sensors (L&R) 4-Zone Sensors There are 18 (including rear) air control flap position sensors in the 4-Zone Cayenne air distribution housings: Fresh air/recirculation flap position sensor Defrost flap position sensor Middle vent position sensors (L&R) Side vent position sensors (L&R) Floor vent position sensors (L&R) Temperature flap position sensors (L&R) Rear temperature flap position sensors (L&R) Rear air flap position sensors (L&R) Rear middle vent position sensors (L&R) Rear side vent position sensors (L&R) The sensor is supplied a 5.0 Volt reference voltage. An increase in sensed solar radiation causes the Climate Control Unit to command an increase in blower speed. The solar sensor is located on the top of the dash in the center. Notes: Climate Control Systems Diagnosis & Repair Page 4.17

82 Cayenne Systems (E1) Actuators Air Control Flap Motors Compressor Solenoid Regulator Valve The seven cylinder variable displacement A/C compressor is controlled by a solenoid regulating valve mounted on the compressor. The regulating valve is duty-cycle controlled by the Climate Control Unit at a frequency of 400 Hz. Changes in heat load cause the Climate Control Unit to vary the duty cycle. Compressor displacement ranges from virtually 0% to 100%. There is no compressor clutch. The compressor shaft always turns with the engine. The solenoid regulating valve varies compressor displacement by changing pressure in the crankcase under the pistons. Increasing or decreasing crankcase pressure allows the angle of the swash plate to vary. No signal or voltage to the regulating valve sets compressor displacement near 0%. Compressor displacement increases to a maximum of 100% as the duty cycle increases. Fresh Air Blower Air control flaps in the air distribution housing are moved by air control flap motors. These are electric motors that are moved on commands from the Climate Control Unit. There are 7 air control flap motors in the Cayenne 2-zone air distribution housing: Fresh air/recirculation flap motor Defrost flap motor Middle vent motor Side vent motor Floor vent motor Temperature flap motors (L&R) The fresh air blower moves air through the air distribution housing. Models with the optional 4-Zone automatic climate control system add a rear heating/cooling unit which includes a rear blower. Blower speed is controlled by the blower regulator. The Climate Control Unit outputs a signal to the blower regulator to set the appropriate blower speed. The blower regulator is located on the air distribution housing on the right side near the blower. A heat-sink on the back side of the blower regulator is placed in the housing airstream to prevent overheating of the module. Do not operate the blower with the blower regulator out of the airstream or with the vehicle fresh air inlet blocked. Blower voltage increases with increased solar load to compensate for the increased solar radiation. There are 10 air control flap motors in the 4-Zone Cayenne air distribution housing: Fresh air/recirculation flap position sensor Defrost flap position motor Middle vent position motors (L&R) Side vent position motors (L&R) Floor vent position motors (L&R) Temperature flap position motors (L&R) Models with the optional 4-Zone system have 8 additional air control flap motors in the rear heating/cooling unit: Rear temperature flap motors (L&R) Rear air flap motors (L&R) Middle vent motors (L&R) Side vent motors (L&R) Page 4.18 Climate Control Systems Diagnosis & Repair

83 Cayenne Systems (E1) Service and Diagnosis Information Moisture condensing on the cold evaporator fins drains out the bottom of the air distribution housing. Be sure that this drain does not become obstructed or plugged. Water coming from outlets at high blower fan speeds can indicate drain blockage. Evaporator fin temperatures cannot be allowed to drop below the freezing point of water. If this happens, the evaporator can become blocked with ice and airflow can be reduced. In Cayenne models, evaporator temperature is maintained by varying compressor displacement. This controls the amount of refrigerant pumped through the system and refrigerant pressure and temperature in the evaporator. These systems are very tolerant of faults and can be difficult to diagnose. Cayenne On Board Diagnostics CAN Bus Comfort High and Low The Climate Control Unit receives information over the CAN Bus from sensors which are not directly connected to the control unit. The control unit also provides climate control information to other components on the CAN Bus. Information received by the Climate Control Unit over the CAN Bus: Ignition ON (Terminal 15) Park Heater ON/OFF Country-specific information Temperature units Outside temperature Dimming signal Vehicle speed Terminal X Heated rear window actual value Windshield wiper Steering angle System information (e.g. MONO function) Engine speed Time Engine temperature Shutdown and reduction request Information placed over the CAN Bus by the Climate Control Unit: The Climate Control Unit monitors its own function and also various sensors and actuators. If a fault is detected, a fault code is stored in non-volatile memory (EEPROM). Sensor circuits are checked for signal plausibility and also whether the signal is within range. If a sensor circuit fault is detected, the system ignores the signal and substitutes a stored default value. In this way, emergency operation of the climate control system can be maintained. RPM increase (to stabilize the idle when the A/C compressor is requested) Heated rear window Compressor status Heater OFF Refrigerant pressure Request condenser cooling ECON function Status of the engine residual heat function Booster heater (not used, value is always 0) Windshield heater Outside temperature Compressor load calculation Blower load KD fault Climate Control Systems Diagnosis & Repair Page 4.19

84 Cayenne Systems (E1) Notes: Page 4.20 Climate Control Systems Diagnosis & Repair

85 Cayenne Systems (E2) Subject Page General Info Automatic Climate Control Air and Flap Control Operation Front Climate Control Unit Operation, 2-Zone & 4-Zone Rear Climate Control Unit Operation, 4-Zone Extended Air-Conditioning Functions Setting and Controlling The Rear Climate Zones Refrigerant Circuit Actuators and Sensors Seat Ventilation Heated Steering Wheel Auxiliary Heater Climate Control Systems Diagnosis & Repair Page 5.1

86 Cayenne Systems (E2) Notes: Page 5.2 Climate Control Systems Diagnosis & Repair

87 Cayenne Systems (E2) Cayenne A/C System Description General The Cayenne in model year 2011 is equipped with 2-zone automatic climate control as standard for all models. 4- zone automatic climate control and an auxiliary heater are also available as optional equipment. All air conditioning functions that are familiar from the previous model will also be available to customers in the future. The climate control system therefore includes the usual air quality sensor for automatic air recirculation control and a residual engine heat function to heat the passenger compartment for up to 20 minutes after the engine is switched off. Operation of the air-conditioning system is also based on the operating concept of the Panamera. In addition to an increase in comfort, some changes have been made in the area of air conditioning due to the close association with the Panamera concept. Even the extended air-conditioning functions listed below, which are accessed and adjusted via the multi-function display in the instrument cluster, are available on all Cayenne models (see also section Operation ). Extended air-conditioning functions: Automatic air-recirculation mode Air flow adjustment Extended ventilation panel In order to implement the extended ventilation panel on the Cayenne from model year 2011, a slight modification of the air and flap control and the air guide was required. Ventilation Air and Flap Control (heating unit) Automatic Climate Control The basic concept of the front heating unit was retained in spite of the increase in comfort afforded by the extended ventilation panel. The front heating unit supplies conditioned, prepared air to all front air ducts and air vents in the usual way (2-zone automatic climate control). The operating concept adopted for the Cayenne includes the new air-conditioning functions of the Panamera. One example is a condensation sensor that monitors the window temperature and the relative humidity close to the windows on all Cayenne models. Upper air outlet openings of the heating unit from front to rear: Opening for center vents and extended ventilation panel Opening for side air vent (for 2-zone system, B-pillar if necessary) Defrost opening Note! The sensor was fully integrated in the mirror base and is available in the Cayenne for the first time. Climate Control Systems Diagnosis & Repair Page 5.3

88 Cayenne Systems (E2) Air Guide (components integrated into the dashboard) In a 4-zone automatic climate control system, all air vents at the rear (including the B-pillar) are supplied via the rear heating unit (left wheel housing). The function and design of the rear automatic climate control system have not changed to any great extent. The necessary modifications to the ventilation system were primarily made in the connection area of the heating unit (see illustration above) for the air ducts. Most modifications were made behind the frame on the heating unit. The following illustration shows the air duct for the extended ventilation panel (position 1). 1 Servo motor for center (covered, right-hand side) 2 Servo motor for footwell/b-pillar vents (right-hand side) A Air duct temperature sensor (right-hand side) Note! The function and design of the rear heating unit are largely comparable with the previous model. 1 Extended ventilation panel air duct and center vent, right 2 Extended ventilation panel servo motor and center vent, left 3 Extended ventilation outlet, left 4 Outlet for center vent, left A Frame of heating unit B End cap for rear area connection, left (4-zone system only) C Air duct for rear center vent, left (2-zone system only) Page 5.4 Climate Control Systems Diagnosis & Repair

89 Cayenne Systems (E2) Operation Operation of the automatic climate control system in the Cayenne is comparable with operation of the system in the Panamera. Based on the same operating concept, different function groups for adjusting the comfort functions are located on the operator control unit. Front Operating and Air-Conditioning Unit (2 and 4- zone system) Settings for the left and right can be adjusted individually on the operating and air-conditioning units (front/rear): Switch on automatic climate control (AUTO button) Set temperature Set air flow (air quantity) Set air distribution Set heated seats/seat ventilation Function group - A Climate control AC MAX mode AUTO / REAR mode Function group - B/C etc. Hazard warning light Sport Plus Function group - X CAN High/Low Terminal 30 A Air-recirculation mode B Defrost windshield C MONO mode D AC MAX mode E Rear window/mirror heating F AC mode G Display, right H Temperature, right I Air flow, right J Air to windshield, right K Air to side and center vents L AUTO / REAR mode, right (4-zone system only) M Air to footwell, right N Air to footwell, left O AUTO / REST mode P Air to side and center vents Q Air to windshield, left R Air flow, left S Temperature, left T Display, left Notes: Climate Control Systems Diagnosis & Repair Page 5.5

90 Cayenne Systems (E2) Rear Operating and Air-Conditioning Unit (4-zone system) Extended Air-Conditioning Functions It is possible to use the extended air-conditioning functions to adapt the automatic air-conditioning control individually. On the Cayenne, this refers to the following functions: Automatic air-recirculation mode Air flow adjustment Extended ventilation panel The extended air-conditioning functions can be accessed via the multi-function display on the instrument cluster. A Display, left B Temperature, left C Air flow, left D Air to door vent and center vent E Air to door vent and center vent F AUTO mode, left G Air to door vent and footwell H Display, right I Temperature, right J Air flow, right K Air to door vent and center vent L Air to door vent and center vent M AUTO mode, left N Air to door vent and footwell Note! Auto air-recirculation mode was included in the extended air-conditioning functions (a button is not available on the operating and air-conditioning unit). The following section lists a selection of functions from function group A (air conditioning). Defrosting Control ( Auto Defrost ) An defrosting control function is also available in automatic mode in the Cayenne for the first time. A condensation sensor measures the window temperature and the relative humidity close to the windows on all Cayenne models. As a result, the dew point on the windshield can be calculated so that the air flow can be adjusted accordingly to ensure that the windshield does not fog up. Note! The sensor was fully integrated in the mirror base and is available in the Cayenne for the first time. The functions in the multi-function display are selected using the lower lever on the right of the steering column. On vehicles with a multi-function steering wheel, the display can also be operated using the right rotary knob and the buttons on the steering wheel, which can be assigned individually. To access the extended air-conditioning functions, select the options Vehicle, Settings and then Climate control from the main menu in the multi-function display. Page 5.6 Climate Control Systems Diagnosis & Repair

91 Cayenne Systems (E2) Automatic air-recirculation mode: There is a setting that determines whether the fresh air supply is controlled automatically in conjunction with an air quality sensor. Air flow adjustment: The settings low, medium and high can be selected to regulate the intensity of the air flow (air quantity). Extended ventilation panel: There is a setting that determines whether the extended ventilation panel (near the compass) on top of the dashboard is switched on or off. AC MAX Mode In AC MAX mode, the passenger compartment is cooled at maximum power (no automatic mode) in the same way as other models regardless of the current setting: Air flow to the passenger vents on the dashboard Maximum blower speed Coldest possible temperature ( LO appears on the front display) Air-recirculation mode Setting and Controlling The Rear Climate Zones The rear climate zones can be controlled using the following buttons on the front operating and airconditioning unit: 1. AUTO/REAR mode button 2. MONO mode button 3. Child protection button (in the driver s door) Note! > If the air-conditioning compressor is switched off manually or automatically, air-recirculation mode ends after approx. 3 minutes. > If the outside temperature falls below approx. 41 F. (5 C.), air-recirculation mode is deactivated automatically to prevent the windows from fogging up. > Press and hold the AUTO/REAR mode button for approx. 2 seconds. In REAR mode, the word REAR appears on the front display. > The child protection button in the driver's door prevents modification of the rear climate zone settings and disables the rear side windows. Notes: Climate Control Systems Diagnosis & Repair Page 5.7

92 Cayenne Systems (E2) Refrigerant Circuit The function and design of the refrigerant circuit in the Cayenne from model year 2011 are largely comparable with the previous model with no significant differences. Topology of the Air-Conditioning System When it comes to exchanging data with other control units, the air-conditioning system is fully integrated into the various networks and bus technologies (CAN/LIN). The front control panel is connected directly to the MMI and is used as the master for air conditioning. The master obtains its information (e.g. from the rear operating and air-conditioning unit [Slave]) via the LIN bus. Actuators and Sensors Since the function and design of the climate control system in the Cayenne are based on the system in the Panamera, operation of the actuators and sensors is also similar. (Additional information can be found in the model year 2010 Panamera Introbook). Interior Temperature Sensor BKE a Front operating and air-conditioning unit (master) BKE b Rear operating and air-conditioning unit (slave) 1 Heating unit 2 Air quality sensor 3 Sun sensor A Auxiliary heater B i Control units for MMI network C i Control units for CAN network X Chassis control switch The position of the interior temperature sensor has been changed compared to the previous model. The sensor is integrated in the dashboard and must not be covered or taped over. Notes: Page 5.8 Climate Control Systems Diagnosis & Repair

93 Cayenne Systems (E2) Seat Ventilation Heated Steering Wheel Three-stage seat heating is optionally available for the Cayenne at the front and rear. The seat heater heats the center sections of the seat cushions and backrests as well as the side bolsters. The heating in the front and rear can be controlled individually via switches in the operating and air-conditioning unit. Seat ventilation is optionally available for the front seats (only in combination with seat heating). Two fan modules produce a suction effect which draws in the perspiration moisture and transports this away via specially arranged air ducts. The steering wheel heating can be switched on using the button on the rear of the steering wheel when the ignition is on. The message Heated steering wheel on or Heated steering wheel off appears on the multi-function display for approx. 2 seconds after the button is pressed. Seat heating can be switched on when seat ventilation is activated. The function and design of both systems are based on the systems from the Panamera. Note! The seat ventilation cannot be switched on below a seat temperature of 59 F. (15 C). A temperature sensor is located in the surface of the seat. Climate Control Systems Diagnosis & Repair Page 5.9

94 Cayenne Systems (E2) Auxiliary Heater General The auxiliary heater optionally available for all Cayenne models makes it possible to create a pleasant climate before the start of a trip in winter and to also defrost the windshield. The auxiliary heater is based on the principle of an auxiliary water heater and is connected to the cooling circuit of the combustion engine and passenger-compartment heat exchanger. Operation Depending on the version, the customer can switch on the auxiliary heater in different ways at outside temperatures below 59 F. (15 C): Radio remote control Operation of a button in the operating and airconditioning unit (center console) Timer function in the instrument cluster Auxiliary heating mode is switched off when the engine is started (engine speed > 300 rpm) or at the latest after 30 minutes. Remote Control The indicator light (LED) in the auxiliary heater button in the center console lights up when the auxiliary heater is activated by the remote control. Transmission Protocol of the Indicator Light (remote control) Button A is pressed to SWITCH ON the heater (LED lights up green). After button A has been pressed: Light flashes green -> Transmission and switch-on operations were successful (auxiliary heater is ready for operation / auxiliary heater is switched on.) Light flashes red -> Switch-on operation was not successful (e.g. the auxiliary heater is not ready for operation, vehicle is out of range, fault in the system / auxiliary heater is not switched on.) Button B is pressed to SWITCH OFF the heater (LED lights up red). After button B has been pressed: Light flashes red -> Switch-off operation was successful (auxiliary heater deactivated) Note! The heating function is not deactivated when the outside temperature threshold of 59 F. (15 C) is exceeded in auxiliary heating mode. Button A must be pressed to switch on the auxiliary heater with the remote control. The LED lights up green. The auxiliary heater is switched off by pressing the Off button B. The LED lights up red. The maximum range (approx. 500 m) of the hand-held transmitter depends on the charge state of the battery as well as on possible interference from buildings and the general surroundings. Page 5.10 Climate Control Systems Diagnosis & Repair

95 Cayenne Systems (E2) Operation of a Button in the Operating and Air- Conditioning Unit (center console) Timer Function in the Instrument Cluster If the ignition is switched on, the auxiliary heater can be switched on and off on the multi-function display (see Owner s Manual for operating steps). In addition, it is possible to program three times (timer) for switching on the auxiliary heater in the future. After the settings have been made for: Time Date it is then necessary to confirm an input (timer). Selection and confirmation of a timer activates the auxiliary heater. The indicator light in the auxiliary heater button on the center console flashes to confirm this. The indicator light (LED) in the auxiliary heater button in the center when the button in the operating and air-conditioning unit is pressed to switch on the auxiliary heater. The auxiliary heater is switched off when the button is pressed again (LED in the button goes out). Note! The indicator light (LED) in the auxiliary heater button in the center when the auxiliary heater is activated by the timer. Note! If a "timer" is active, the indicator light flashes when the ignition is switched off until the vehicle is locked or for a maximum of 30 seconds after activation by the timer. The auxiliary heater does not switch to operational readiness mode if the fuel gauge is in the reserve range (<3 gal. /12 liters). Notes: Climate Control Systems Diagnosis & Repair Page 5.11

96 Cayenne Systems (E2) Heating Unit of the Auxiliary Heater (4-zone system) The auxiliary heater (heating unit) is manufactured by Eberspächer. Most components are located behind the wheel-housing trim panel at the front left. The heating unit of the Cayenne has the same function and design as the heating unit on the Panamera. Water Pump The electric water pump (circulating pump) is located under the heating unit. This circulating pump runs when the auxiliary heater is active and permits circulation of the heated water through the passenger compartment heat exchanger (small water circuit). The circulating pump is controlled directly by the operating and air-conditioning unit (OAU = control unit of the air conditioning system). 3/2 Directional-Control Valve (volumetric flow) Water flows through the passenger compartment heat exchanger when the auxiliary heater is active (small water circuit). The 3/2 directional-control valve isolates the large water circuit (engine cooling) for this purpose. As a result, the control unit for the auxiliary heating system controls the directional-control valve directly (valve is energized, armature at top). The auxiliary heater is not designed for engine preheating at present. 1 Heating unit (auxiliary heater) 2 Intake air silencer 3 Pipe to exhaust silencer 4 Circulating pump (holder) 5 Fuel pipe 6 3/2 directional-control valve (change-over valve) Note! The heating current is between 2.3 and 5.0 kw. The power consumption for this is between 12.5 and 37 W (values for partial and full load). The electric power may reach 200 W momentarily in starting mode. A 3/2 directional-control valve (change-over valve) B Heating unit (auxiliary heater) C Rear heat exchanger connection D Large water circuit connection E Circulating pump F Front heat exchanger connection 1 Volume flow after the circulating pump 2 Volume flow after heating unit and to front heat exchanger (heated supply) 3 Volume flow after front heat exchanger 4 Volume flow to circulating pump Page 5.12 Climate Control Systems Diagnosis & Repair

97 Cayenne Systems (E2) The volume flow (pos 4) can only flow towards the intake end of the circulating pump because the large water circuit is isolated. Auxiliary Heater Metering Pump Topology of the Auxiliary Heater The auxiliary heater is connected to the CAN MMI. The following diagram shows which control units supply data or information for auxiliary heating operation. The metering pump of the auxiliary heater is located behind the rear cross-member on the left side of the vehicle and is mounted on the underbody assembly. The intake side line of the metering pump is attached on the right side of the fuel tank and pumps fuel directly out of the pump chamber. The aspirated fuel is pumped to the heating unit on the auxiliary heater through a line mounted on the left side member. The metering pump is controlled and clocked directly by the control unit of the auxiliary heater. 1 Metering pump 2 Metering pump connector A Pressure-side line connection B Intake-side line connection SH Auxiliary heater control unit BKE Operating and air-conditioning unit (front) A i CAN network control units B Airbag C Engine electronics (DME) D Front-end electronics E Combined steering column module F Instrument cluster (master) 1 Multi-function display 2 Metering pump 3 3/2 directional-control valve (change-over valve) 4 Circulating pump 5 Air flow (fan) 6 Heating unit (air conditioner servo motors) a Crash signal (airbag) b Engine speed c Terminal 15/50/75 d Combined steering column module stalk e Fuel level f Antenna g Amplifier h Radio receiver i Outside temperature sensor (NTC) j Auxiliary heater button (center console) CAN i CAN Network CAN A CAN Drive CAN B CAN Comfort CAN MMI CAN Man Machine Interface Climate Control Systems Diagnosis & Repair Page 5.13

98 Cayenne Systems (E2) Task Distribution for Auxiliary Heater Notes: The following list provides an overview of the (main) tasks of the individual control units during auxiliary heater operation. Instrument Cluster (master) Operation/activation of the auxiliary heater via the multifunction display Programming a timer (timer in the gateway) Signal output for activation of the auxiliary heater (check of switch-on conditions is necessary) Output of messages and warnings Auxiliary Heater (control unit) Input for switch-on and switch-off signals from the remote control and forwarding via CAN MMI to the instrument cluster (master) Activation of the auxiliary heating function (request from master [instrument cluster] is necessary for this) Control of internal heating processes including fuel metering (e.g. activation of the metering pump) for heating operation Operating and Air-conditioning Unit (front) Forwarding of the request or deactivation signal from the auxiliary heater button in the center console Controlled warm air distribution (warming-up and defrosting) Control of the actuators (e.g. passenger-compartment fan, servo motors and water pump) Gateway Signal for activation of the auxiliary heater after check of switch-on conditions (e.g. energy management) Timer Signal routing Note! The 3/2 directional-control valve is controlled directly by the auxiliary heater control unit in the Cayenne! Page 5.14 Climate Control Systems Diagnosis & Repair

99 Cayenne S Hybrid Systems (E2) Subject Page General Info Electric Auxiliary Systems Overview of Air-Conditioning Compressor Electric Drive Scroll Compressor Climate Control Systems Diagnosis & Repair Page 6.1

100 Cayenne S Hybrid Systems (E2) Notes: Page 6.2 Climate Control Systems Diagnosis & Repair

101 Cayenne S Hybrid Systems (E2) Cayenne S Hybrid A/C System Description General The Cayenne S Hybrid has many design features that utilize the high-voltage system in the vehicle. For example, the Cayenne S Hybrid has neither a 12 V generator nor an electric 12 V starter, as these components are replaced by the hybrid module, which is operated at 288 V. The Cayenne S Hybrid can be driven purely on electric power thanks to its full parallel hybrid drive. After the combustion engine is switched off, various components, which are normally powered by the combustion engine, must be powered electrically. Electric Auxiliary Systems The Cayenne S Hybrid has the following electric auxiliary systems: Electrohydraulic servo pump Electric vacuum pump (brake booster) Spindle actuator (decoupler control) Electric air-conditioning compressor Goals Air conditioning function even when the combustion engine is switched off through electrical operation of the air-conditioning compressor Reduced fuel consumption through demand-based regulation of the air-conditioning compressor Special Features The air-conditioning compressor is powered electrically to allow vehicle air conditioning even when the combustion engine is switched off and is an exception among the afore-mentioned electrically powered components, as it has a different nominal voltage (288 V) and internal design compared with conventional air-conditioning compressors. Technical Data Maximum cooling output Maximum power consumption Operating voltage Operating speed range 7.6 kw 4.05 kw 288 V 800-8,600 rpm Note! The safety instructions must be observed during work on the Cayenne S Hybrid. All work on hybrid vehicles may only be performed by qualified staff. Further information is provided in the Cayenne S Hybrid Training Information and in the PIWIS Information System. 1 Electric vacuum pump 2 Electric air-conditioning compressor 3 Electrohydraulic servo pump 4 Spindle actuator Climate Control Systems Diagnosis & Repair Page 6.3

102 Cayenne S Hybrid Systems (E2) Overview of Air-Conditioning Compressor 1 Electrical connection CAN-MMI and 12 V power supply 2 Electrical connection, high-voltage lines, shielding line and pilot line 3 Inverter and driver (driver electronics) 4 Low-pressure connection 5 High-pressure connection 6 Compressor housing Electric Drive Unlike conventional air-conditioning compressors, the scroll compressor used here does not run with the combustion engine, but is instead only operated via an electric motor as required. In other words, the compressor only produces a power loss when cooling power is actually to be produced. This means: Reduced load on the vehicle electrical system electronics due to low current consumption Less wear on the air-conditioning compressor This results in additional fuel consumption savings. 1 Terminal voltage connections 2 Inverter connection with shielding line and pilot line The scroll compressor is supplied with a voltage of 288 V DC from the power electronics of the high-voltage system via a high-voltage cable to drive the integrated electric motor. The energy required to drive the brushless direct-current motor (see Group 2, section Hybrid Technology, Principles) is converted by the inverter from DC voltage (288 V) to a 3-phase AC voltage (alternating voltage) of 280 V. The three-phase motor is supplied with power via three phases and drives the scroll compressor wheel, which compresses the refrigerant. The driver electronics are, like the inverter, integrated in the upper section of the compressor housing. They are supplied with a 12 V power supply, which is switched via terminal 15, and receive commands from the airconditioning control unit via the MMI bus. The air-conditioning compressor is diagnosable. Page 6.4 Climate Control Systems Diagnosis & Repair

103 Cayenne S Hybrid Systems (E2) Scroll Compressor The air-conditioning compressor compresses the refrigerant with the aid of a scroll compressor instead of the swash plate that is used with conventional air-conditioning compressors. The scroll compressor consists of two interleaved scrolls, one of which is fixed while the other moves in a circular motion within the fixed scroll. The scrolls almost come into contact with one another many times and form multiple continuously increasing and decreasing chambers within the scrolls. The refrigerant to be compressed passes through these changing pockets until it reaches the center of the compressor. Here, the compressed refrigerant is then discharged and fed to the refrigerant circuit in a pressurized state. 1 Inverter 2 Low-pressure connection (inlet) 3 Brushless direct-current motor 4 Scroll compressor wheel 5 Oil collection chamber 6 Venturi oil separator 7 High-pressure connection (outlet) To separate the ND8 oil, an oil separator that functions according to the Venturi principle is used at the highpressure outlet. The rest of the air-conditioning system is based on the conventional design. Climate Control Systems Diagnosis & Repair Page 6.5

104 Cayenne S Hybrid Systems (E2) Notes: Page 6.6 Climate Control Systems Diagnosis & Repair

105 Panamera Systems Subject Page General Information Cayenne vs. Panamera System Differences Heating Unit Temperature Mixing Chamber Air Ducts Air Distribution Modular Operator Control Panel Operating and Air-Conditioning Unit, Front Extended Air-Conditioning Functions Operating and Air-Conditioning Unit - 4-Zone, Rear Operating and Air-Conditioning Unit - 2-Zone, Rear Refrigerant Circuit Air-Conditioning Network Topology Actuators and Sensors Seats - Heating and Ventilation Heated Steering Wheel Climate Control Systems Diagnosis & Repair Page 7.1

106 Panamera Systems General Information The Panamera is equipped with 2-zone automatic climate control as standard. 4-zone automatic climate control is available as an option for all Panamera models. The following functions can be set on an individual basis for all climate controlled areas: Temperature Air distribution Air flow The required temperature is adjusted automatically. To prevent the windows from misting, the humidity is first of all measured and taken into consideration. The climate control also features automatic air-recirculation control, utilization of residual engine heat, AC MAX mode, MONO mode and individually adjustable extended air-conditioning functions. A cooled glove box also comes as standard. Overview of the Climate-Related Equipment Equipment Panamera/S Panamera 4/4S Panamera Turbo Page 7.2 Climate Control Systems Diagnosis & Repair

107 Panamera Systems Cayenne vs. Panamera A/C System Note: Rear passenger adjustments (especially changing the strength of the fan) can lead to feedback in the front airconditioned areas Refrigerant Circuit The function and design of the refrigerant circuit. Cayenne air-conditioning system (2+2 air-conditioning system): Rear air vents (footwell, center console and B-pillar) are served by a separate heating unit (shown here) Advantage: Passenger adjustments in the rear do not impact on the front air-conditioned areas Note: High additional weight (e.g. heating unit) Large amount of space required Additional lines (e.g. air-conditioning line) High cost 1. Compressor (electronically controlled) 2. Condenser 3. Holder (pipe) for dryer cartridge 4. Pressure sensor 5. Expansion valve input (high pressure) 6. Expansion valve output (low pressure) A - Service connection (high pressure) B - Service connection (low pressure) Red Arrow - Heat exchanger connection Blue Arrow - Evaporator connection Notes: Panamera air-conditioning system (4-zone system): All air vents in the vehicle (incl. the rear) are served by just one air-conditioning unit (heating unit at front) Advantages: More cost-effective Weight advantages Less space required Climate Control Systems Diagnosis & Repair Page 7.3

108 Panamera Systems Heating Unit (2-zone and 4-zone) The heating unit is similar in some respects to the heating unit in the Cayenne. However, as this system provides all areas with air conditioning using one heating unit, the heating unit design is more complex and not comparable. Heating Unit Air Intake a - Intake air temperature sensor b - Particle filter with active carbon coating Distinguishing between the 2- and 4-zone heating unit by the number of servo motors: A total of 15 servo motors are integrated in the 2-zone system. A total of 19 servo motors are integrated in the 4-zone system. Heating Unit Air Outlet 1. Servo motor for fresh air/recirculated air 2. Servo motor for ram air The fresh-air/recirculation flap and the ram-air flap each have a servo motor located directly beside the air intake opening of the heating unit. The particle filter is positioned at the point where the heating unit s air intake opening connects with the air-mixing/distribution chamber (view in direction of air movement). To change the particle filter (for maintenance) a service opening is located in the housing of the heating unit (similar to the Cayenne). The opening can be reached by removing the knee guard on the passenger's side. A. Servo motor for extended ventilation 1. Defroster, left/right 2. Side passenger air vent, left 3. Side passenger air vent, right 4. Extended ventilation, left/right 5. Center passenger vent, left 6. Center passenger vent, right 7. Left footwell 8. Right footwell 9. Rear left 10. Rear right Only one servo motor is available for extended ventilation. Both air flow flaps are activated using this drive link. Page 7.4 Climate Control Systems Diagnosis & Repair

109 Panamera Systems Heating Unit, Left Side Heating Unit, Right Side 1. Servo motor for front side air vent 2. Servo motor for front temperature mixing flaps (cold and hot flap) 3. Servo motor for rear temperature mixing flaps (cold and hot flap) 4. Servo motor for front center vent left/right (cold air metering for bypass duct) 5. Servo motor for front footwell 6. Servo motor for front center vent A. Evaporator B. Heat exchanger C. Condensation outlet a. Temperature sensor, front footwell Additional cold air can be fed to the center vent through a bypass duct). The temperature sensor for the side air vent (one each on the right/left side) is not positioned directly on the heating unit. The sensors are located in an intermediate piece just behind the air vents of the heating unit. This intermediate piece (connector) is an integrated component of the underside of the switch panel and routes the air flow to the air ducts, which serve the side air vents (right/left switch panel). 1. Servo motor for defroster, left/right 2. Servo motor for front side air vent 3. Servo motor for front footwell 4. Servo motor for front temperature mixing flaps (cold and hot flap) 5. Servo motor for rear temperature mixing flaps (cold and hot flap) - this drive link is located below item 4 a. Temperature sensor, front footwell The servo motor for the temperature mixing flap at the rear is located below position 4. The arrow points only to the connector for this drive link. Notes: Climate Control Systems Diagnosis & Repair Page 7.5

110 Panamera Systems Temperature Mixing Chamber (front and rear) 1. Defroster 2. Side air vent 3. Center vent (not on sectional plane) A. Evaporator B. Heat exchanger C. Hot flap(s) D. Cold flap(s) E. Air flow flap 4. Extended ventilation (Front vented) 5. Rear output The temperature-mixing chamber is a symmetrical structure. This means that there are temperature mixing flaps for the left and right side at the front and rear (see section on the left side). Air Ducts Behind the evaporator, the entire air flow is routed separately for the front and rear by the respective temperature mixing flap system (cold and hot flaps) into the temperature-mixing chamber behind. The cold and hot flaps are connected and actuated by a servo motor (temperature mixing flap). All flap positions are adjustable depending on the temperature required. Example: Cold flap OPEN max <=> Hot flap CLOSED max Depending on the setting (automatic or manual mode) the air flows from the various temperature-mixing chambers (four in total) are routed separately through the air flow flaps in the heating unit to the individual vent ducts. An air flow flap for the rear is located in the air distributor. 1. Fresh air intake tubes 2. Heating unit (indicated) 3. Air distributor (left/right) A. Air quality sensor B. POS Temperature sensors, side air vents (left/right) All air ducts are served by one heating unit. An air distributor (only indicated here) also distributes the air flows towards the rear vents. Position of the temperature sensor on the side air vent: Page 7.6 Climate Control Systems Diagnosis & Repair The temperature sensor for the side air vent (one each on the right/left side) is not positioned directly on the heating unit. The sensors are located in an intermediate piece just behind the air vents of the heating unit. This intermediate piece (connector) is an integrated component of the underside of the switch panel and routes the air flow to the air ducts, which the side air vents (right/left switch panel) serve

111 Panamera Systems Air Distributor Modular Operator Control Unit The air flow for the rear is distributed via a distributor to the vents. There are two flaps and the associated servo motors (3x) on the air distributor housing: Air distribution flap in footwell/center (1) Air flow flap (2) Directions of air flow (distributor outlets): x - Air flow to footwell vent y - Air flow to center vent z - Air flow to B-pillar (always open) In addition, the rear temperature sensor (4) is located on the right and left in the distributor housing. A modular operator control unit in the center console allows you to adjust the air-conditioning functions, operate the chassis settings and perform other control functions (function groups). Several comfort functions are integrated in the Panamera thanks to the new operating concept in the operator control units. The inputs and outputs for these are subdivided into various function groups. Concept of the front operator control unit. (Operator control unit = OCU or OCE*) Function group - A: Settings for air-conditioned areas (e.g. heated/ ventilated seats, automatic mode etc.) Function group - B/C etc.: Safety or chassis functions, their inputs and outputs (e.g. Sport Plus etc.) Function group - X: General inputs and outputs (e.g. CAN High/Low, terminal 30 etc.) Climate Control Systems Diagnosis & Repair Page 7.7

112 Panamera Systems Operating and Air-Conditioning Unit (OAU, front) 4-Zone System The influence of the Carrera GT can be seen in the center console. The idea to transfer almost all of the switches from the switch panel to the center console simplifies operation for the driver. The most important functions are sorted into function groups for fast, uncomplicated and intuitive operation. The driver s inputs are evaluated by these controls (buttons and sliders) in the operating and air-conditioning unit and forwarded to the relevant control units in the various function groups. The operating and air-conditioning unit also regulates and controls all the heating and air-conditioning system components required for cabin air conditioning. Feedback is provided through the control panel (e.g. LED button lights up/display at the front). Air-conditioning functions - A Safety functions - B Chassis functions - C Body functions - D A distinction can be made between the following versions: a) OAU with automatic 2-zone adjustment Automatic adjustment (left/right) with different temperature, air flows and air distribution for driver and passengers b) OAU with automatic 4-zone adjustment This automatic adjustment also enables single seat air conditioning with independent temperature, air flow and air distribution control for all four seats. A second OAU is used to operate these functions in the rear. Both OAUs are connected via the LIN bus. Notes: Page 7.8 Climate Control Systems Diagnosis & Repair

113 Panamera Systems Operating and Air-Conditioning Unit (OAU, front) 4-Zone System Anti-Mist Control ( Auto Defrost ) An anti-mist control function is also available for the first time in the Panamera in automatic mode. As part of this function, a sensor records the humidity in the vehicle. The sensor for anti-mist control is located at the base of the rearview mirror. With manual windshield defrosting (defroster), the air supply to the rear is cut off automatically in defrost mode to achieve maximum defrosting efficiency in the 4- zone system. OFF appears on the rear OAU display. In the 2-zone system, the windshield is defrosted with maximum efficiency when the air vents in the rear are closed. When outside temperatures < 27 F. (-3 C.) or the intake air temperature <36 F. (2 C.), the compressor is switched off automatically. The heated rear window/door mirror heating function is available when the engine is running (indicator light in the button is illuminated). Depending on the outside temperature, the heating switches off automatically after approx. 5 to 20 minutes. The heating can be switched back on by pressing the button again. Button assignment for air-conditioning functions (individually for left/right): - Switch on climate control (AUTO button) - Set temperature - Set air quantity (air volume) - Set air distribution - Set heated seats/seat ventilation The heated rear window/door mirror heating function is available up to an outside temperature of 86 F. (30 C.). Air-Recirculation Control The outside air/fresh air supply is interrupted. If the airconditioning compressor is switched off manually or automatically, air-recirculation mode ends after approx. 3 minutes). Automatic Air-Recirculation Control The air-recirculation mode is adjusted automatically depending on the air quality (air quality sensor). Automatic air-recirculation mode can be switched on and off. Antimist control terminates air-recirculation control if necessary. Terminating the air-recirculation control when the compressor is switched off and the anti-mist control (measuring the humidity) prevent the windows from misting. The recommended operating mode is automatic air-recirculation mode (default setting). Climate Control Systems Diagnosis & Repair Page 7.9

114 Panamera Systems Automatic Air-Recirculation Control (cont d) When the outside temperature < 50 F. (10 C.), air-recirculation mode is deactivated automatically to prevent the windows from misting. The maximum recirculation period request by the air quality sensor is 14 minutes. The air moisture sensor is an integrated component of the rain-light-moisture sensor. This is located at the base of the rearview mirror and detects: Precipitation events for wiping cycle requirements The light sensor (light/dark) for driving light requirements Humidity for clearing misted windows MONO Mode ( MONO button) All air-conditioned areas depend on the setting of the driver s air-conditioned area. The three displays change their values. AC MAX Mode ( AC MAX button) In AC MAX mode, the passenger compartment is cooled at maximum power (no automatic mode). In MONO mode, the indicator light is illuminated until the MONO button is pressed again. The values that are set are maintained for all areas (no memory for the original settings). MONO mode is also exited if a setting in an air-conditioned area (not the driver's area) is changed. In AC MAX mode in a 4-zone system (when the indicator light is illuminated on the button), maximum cooling power is focused on the two areas in the front. The air conditioned areas in the rear are deactivated automatically to achieve this increase in cooling power. OFF appears on the rear OAU display. The following conditions are automatically set for rapid cooling: Residual Engine Heat Utilization ( AUTO REST button) The residual heat of the engine can be used to heat the interior for up to 20 minutes after the ignition has been switched off. The indicator light on the button lights up in REST mode. The settings for the air-conditioning system (e.g. fan speed) cannot be changed manually. Note! If the battery voltage is too low, REST mode is restricted initially and then switched off. Setting and Adjusting Climate Control For Rear Areas With The Front Operator Control Unit Changing the air-conditioned areas at the rear with the front operating and air-conditioning unit: 1) AUTO REAR button Press the button for approx. 2 seconds. In REAR mode, the word REAR appears on the display. 2) MONO button For more information, see MONO mode. The REAR mode function switches off automatically approx. 4 seconds after the last settings are configured. REAR mode can also be switched off manually. To do this, press the AUTO REAR button in the front OAU for approx. 2 seconds. Note! > The rear OAU can also be switched on/off using the child protection button AA (driver s door). A lock symbol appears on the display. > The power window buttons on the rear doors and the control panel (all function groups) on the center console can be deactivated by pressing the safety button (child protection) in the keypad on the driver s door. Most of the air (air flow) is routed to the passenger air vents in the switch panel Maximum fan speed Coldest possible temperature ( LO appears on the front display) Air-recirculation mode Page 7.10 Climate Control Systems Diagnosis & Repair

115 Panamera Systems Extended Air-Conditioning Functions The Extended air-conditioning functions setting on the on-board computer can be configured using the small thumb wheel (on the right) on the steering wheel. Once the vehicle/settings/air conditioning has been selected, the options listed below can be set. In the Panamera, the extended air-conditioning functions listed below are available in conjunction with the 14-way power seats with memory package and can be set individually. The settings can be configured using the combination control stalk on the on-board computer of the instrument cluster (multi-function display). Adjusting Air Flow Three settings ( low, medium and high ) are available in automatic mode to regulate the intensity of the air flow. Extended Ventilation Panel (middle of the switch panel) This ventilation panel can switch on and off. Switching Automatic Air-Recirculation Mode on/off You can configure the fresh air supply to adjust automatically to the air quality (air quality sensor). Setting Center Vent to Blow Colder Air A bypass duct is located in the heating unit for this purpose. The preset interior temperature remains the same. Notes: Climate Control Systems Diagnosis & Repair Page 7.11

116 Panamera Systems Operating and Air-Conditioning Unit (OAU, rear) 4-Zone System The operating and air-conditioning unit (OAU) in the center console at the rear of the vehicle allows you to set the air-conditioning, safety and comfort functions. The OAU is only available in vehicles with 4-zone systems and is connected to the front OAU via the LIN bus. Feedback is provided through the control panel (e.g. LED button lights up/display at the rear). The buttons for the heated seats and seat ventilation are designed as three-stage buttons and can be adjusted individually for each seat (for more information, see Seat air conditioning ). Depending on the equipment in the vehicle, additional buttons for adjusting the backrests and seat cushions (passenger) are available in the top middle section of the OAU. Also available are options for adjusting the roll-up sunblind for the rear window and actuating the central locking system. Depending on the equipment, various trims are available for the control unit (operator control unit). Note! The control buttons can also be assigned to individual function groups on the rear operator control unit. > The picture of the rear OAU is not correct. In the 4-zone system, there is no button for heated seats or seat ventilation in function group F. > The buttons for the individual function groups may differ, depending on the various options that can be ordered (e.g. with and without heated seats). Air-conditioning functions - A (only in 4-zone systems) Safety functions - B Comfort functions - F (passenger seat adjustment) Button assignment for air-conditioning functions (individually for left/right): - Switch on climate control (AUTO button) - Set temperature - Set air quantity - Set air distribution - Set heated seats/seat ventilation Page 7.12 Climate Control Systems Diagnosis & Repair

117 Panamera Systems Operating and Air-Conditioning Unit (OAU, rear) 2-Zone System The operator control unit (OCU) in the center console at the rear of the vehicle allows you to operate various function groups, depending on the equipment. Buttons may be available for adjusting the roll-up sunblind for the rear window, actuating the central locking system or adjusting the heated seats and seat ventilation, available as optional extras. Depending on the equipment, various trims are available here for the control unit (OCU). The operator control unit is connected to the front operator and air-conditioning unit via the LIN bus. Feedback is provided through the control panel (e.g. LED button lights up/display at the rear). The control buttons can also be assigned to individual function groups on the rear operator control unit. Safety functions - B Comfort functions - F (passenger seat adjustment) The buttons for the individual function groups may differ, depending on the various options that can be ordered (e.g. with and without heated seats). Notes: Climate Control Systems Diagnosis & Repair Page 7.13

118 Panamera Systems Refrigerant Circuit (2-Zone and 4-Zone System) 1. Compressor (electronically controlled) 2. Condenser 3. Mounting (pipe) Dryer cartridge 4. Pressure sensor 5. Expansion valve input (high pressure) 6. Expansion valve output (low pressure) A. Service connection (high pressure) B. Service connection (low pressure) Heat exchanger connection With the electronically controlled compressor and condenser with integrated mounting for the dryer equipment (dryer cartridge), the refrigerant circuit is similar to that in the Cayenne. The electronic control valve in the compressor is actuated by the OAU. The OAU uses the evaporator temperature sensor value as the main input variable for the actuation. When outside temperatures < 27 F. (-3 C.) or the intake air temperature < 36 F. (2 C.), the compressor is always switched off automatically. Compressor Switch-off Conditions Codes The compressor s OFF code uses the PIWIS Tester to assign the reason for switching off. If the charging condition of the battery is critical, the following air-conditioning functions are restricted initially and then switched off: Heated seats Heated rear window/door mirror heating Fresh air fan Air-conditioning compressor Codes 0 - OK (no switch-off condition) 1 - High-pressure cut-off 2 - Low fan speed 3 - Low-pressure cut-off 4 - ECON 5 - Engine start 6 - ECON mode 7 - AC off (fan OFF) 8 - Outside temperature 9 - Not used 10 - Low battery voltage 11 - High engine temperature 12 - Engine control module (engine temperature is too high) 13 - High battery voltage 14 - Evaporator temperature sensor (risk of freezing) 15 - Three overpressure events 16 - Servo motor fault (e.g. servo motor) 17 - Pressure sensor fault 18 - Overheating protection (if engine speed is too high) 19 - Vehicle electrical system control unit requirement 20 - Low refrigerant level 21 - Compressor run-in period (end of assembly line) 22 - Run-in period is not yet completed Note! Since the compressor system is similar to that in the Cayenne, the OFF code can also be used for diagnosis purposes. Code 8: When outside temperatures < 27 F. (-3 C.) or the intake air temperature < 36 F. (2 C.), the compressor is always switched off automatically Code 12: Switch-off request from the DME control unit (e.g. when T_Mot >244 F. (118 C.) Code 19: Switch-off request from battery control unit or vehicle electrical system control unit Code 21: During the run-in period, the compressor is switched off if the engine speed of >1200 rpm is exceeded Page 7.14 Climate Control Systems Diagnosis & Repair

119 Panamera Systems Air-Conditioning Network Topology When it comes to exchanging data, the air-conditioning system is fully integrated into the various networks and bus technologies (CAN/LIN). The front control panel is connected directly to the CAN MMI and is used as the master for air conditioning. The master obtains its information (e.g. from the rear OAU) via the LIN bus. Information required from other CAN bus areas is provided via the gateway s bus interfaces (e.g. engine temperature). Bus speeds in the Panamera: CAN drive 500 Kbaud CAN crash risks 500 Kbaud CAN diagnosis 500 Kbaud CAN chassis 500 Kbaud CAN comfort 500 Kbaud CAN MMI 500 Kbaud (MMI = Man Machine Interface) LIN 20 Kbaud Notes: Climate Control Systems Diagnosis & Repair Page 7.15

120 Panamera Systems Actuators and Sensors (front OAU in the 4-zone system) Page 7.16 Climate Control Systems Diagnosis & Repair

121 Panamera Systems Actuators and Sensors (rear OAU in the 4-zone system) Additional Information Pressing the Auto REST and Auto REAR buttons briefly starts automatic mode on the left and right. The sensor for measuring humidity in the cabin is located at the base of the rearview mirror. Additional sensors are also located here (e.g. light sensor). The servo motors for the temperature mixing flaps each actuate a cold and hot flap for the front and rear (linked). Example: Cold flap OPENmax <=> Hot flap CLOSED max Air moisture sensor/front BCM/CAN comfort/gateway/can MMI/front OAU Engine speed/dfi control unit/can drive/gateway/can MMI/front OAU The humidity is measured by a sensor integrated in the rain-light-moisture sensor (located at the base of the rearview mirror). In addition to humidity, this sensor also records dew point temperature, the temperature of the windshield, sun intensity on the left and right and the angle of incidence. Wiper stalk activated/combined steering column module (CSCM)/CAN comfort/gateway/can MMI/front OAU Ignition on (terminal 15)/front BCM/CAN comfort/gateway/can MMI/front OAU Climate Control Systems Diagnosis & Repair Page 7.17

122 Panamera Systems Seats - Heating and Ventilation Activation and deactivation of the system is indicated on the on-board computer of the instrument cluster. Steering wheel heating ON or Steering wheel heating OFF The seat heater heats the centers of the seat surfaces and the backrests. The heating operates in three stages and can be controlled separately via switches in the front and rear center console (depending on the design). When the heated steering wheel is activated, the temperature of the steering wheel rim is controlled by a temperature sensor located on the steering wheel rim. When the heated steering wheel is activated, the temperature of the steering wheel rim is kept constant at 95 F. (35 C.) by the combined steering column module (CSCM) through a temperature sensor. 3-spoke sports steering wheel with steering wheel rim in smooth finish leather. 3-spoke multi-function steering wheel in leather. Seat ventilation is also available as an optional extra. The three-stage controllable ventilation system (fan module position 1 and 2) under the perforated seat and backrest center generates an air swirl. The perspiration is thus sucked in and dissipated away through air ducts in the seat. To prevent the occupants from getting too cold, seat ventilation cannot be switched on if the seat temperature is below 59 F. (15 C.). Heated Steering Wheel (Option) The sports and multi-function steering wheel can be equipped with steering wheel heating as an optional extra. The optional multi-function steering wheels in wood and carbon are always equipped with steering wheel heating. The heating for the steering wheel rim can be switched on and off separately using a button on the 6 o clock spoke (subject to release from energy management system). 3-spoke multi-function steering wheel in wood or carbon. Function: Once activated by the button on the 6 o clock spoke, the Heated steering wheel active request is received by the combined steering column module (CSCM) (conventional signal). The NTC signal from the temperature sensor in the steering wheel rim is now sent to the CSCM and is evaluated by it. The CSCM energizes the heating foil/ heating fabric on the steering wheel rim in accordance with this value. Page 7.18 Climate Control Systems Diagnosis & Repair

123 Conversion Charts Temperature Conversion Metric Conversion Formulas INCH X 25.4 = MM MM X.0394 = INCH MILE X = KILOMETER (KM) KM (KILOMETER)... X.621 = MILE OUNCE X = GRAM GRAM X.0352 = OUNCE POUND (lb)... X.454 = KILOGRAM (kg) kg (KILOGRAM) X = lb (POUND) CUBIC INCH X = CUBIC CENTIMETER (cc) cc (CUBIC CENTIMETER)... X.061 = CUBIC INCH LITERS X.0353 = CUBIC FEET (cu.ft.) CUBIC FEET (cu.ft.) X = LITERS CUBIC METERS..... X = CUBIC FEET (cu.ft.) FOOTPOUND(ft lb)..... X = NEWTON METER (Nm) Nm (NEWTON METER) X.7376 = ft lb (FOOT POUND) HORSEPOWER (SAE)... X.746 = KILOWATT (Kw) HORSEPOWER (DIN)... X.9861 = HORSEPOWER (SAE) Kw (KILOWATT) X 1.34 = HORSEPOWER (SAE) HORSEPOWER (SAE)... X = HORSEPOWER (DIN) MPG (MILES PER GALLON)... X.4251 = Km/l (KILOMETER PER LITER) BAR X 14.5 = POUND/SQ. INCH (PSI) PSI (POUND SQUARE INCH).... X.0689 = BAR GALLON X = LITER LITER X.2642 = GALLON FAHRENHEIT = CELSIUS CELSIUS X = FAHRENHEIT Climate Control Systems Diagnosis & Repair Page 8.1

124 Conversion Charts Notes: Page 8.2 Climate Control Systems Diagnosis & Repair

125