Section 12-00: Climate Control System Service 1997 Town Car Workshop Manual DIAGNOSIS AND TESTING Procedure revision date: 06/29/2000 Climate Control System Inspection and Verification 1. Verify the customer's concern by operating the climate control system to duplicate the concern. 2. Inspect to determine if one of the following mechanical or electrical concerns apply: VISUAL INSPECTION CHART Mechanical Loose, missing or damaged A/C compressor drive belt. Loose or disconnected A/C clutch. Loose, misrouted or damaged vacuum lines. Discharged A/C system. Broken or leaking refrigerant lines. Broken or leaking vacuum control motor. Electrical Open fuse. Blower motor inoperative. A/C compressor inoperative. Cooling fan inoperative. Circuitry open/shorted. EATC A/C control inoperative. Disconnected electrical connectors. 3. If inspection reveals obvious concern(s) that can be readily identified, service as required. 4. If the concern(s) remains after the inspection, determine the symptom(s) and go to the Symptom Chart. Symptom Chart Climate Control System Refer to the Electrical and Vacuum Troubleshooting Manual for the connector numbers cited in the pinpoint tests. Use Rotunda 73 Digital Multimeter 105-R0051 or equivalent to perform pinpoint tests. CLIMATE CONTROL SYSTEM Condition Possible Source Action Improper/Erratic Direction of Airflow from Outlets Insufficient, Erratic, or Heat A/C Always On Insufficient A/C Cooling Engine Cooling Fan Does t Operate When A/C is Activated vacuum to A/C control. A/C control leaks vacuum. Damaged/kinked/pinched vacuum hose. Leaking/damaged vacuum control motor. Leaking/damaged A/C vacuum reservoir tank and bracket. Leaking/damaged A/C Vacuum Check Valve. Vacuum actuator arm not connected to door crank. Low radiator coolant level. Engine overheating. Thermostat. Plugged or partially plugged heater core. Inoperative A/C electronic blend door actuator. Circuitry short/open. Damaged A/C cycling switch. Damaged A/C control. Damaged powertrain control module. Improper A/C clutch air gap. Restricted A/C evaporator core orifice. Low refrigerant level. Inoperative A/C cycling switch. Damaged A/C cycling switch. Missing, damaged or mispositioned radiator air seals and aeroshields. Powertrain control module damaged. Fan control (FC) circuitry damaged. Cooling fan motor damaged. GO to Pinpoint Test A. GO to Pinpoint Test B. GO to Powertrain Control/Emissions Diagnosis Manual. GO to Section 12-03B. GO to Refrigerant System Tests. GO to Pinpoint Test C. Pinpoint Tests PINPOINT TEST A: IMPROPER/ERRATIC DIRECTION OF AIRFLOW FROM OUTLETS A1 CHECK SYSTEM AIRFLOW NOTE: The air handling system is designed to provide defrost when no vacuum is applied to any of the three vacuum control motors. This is done to prevent a situation where defrost cannot be obtained due to a system vacuum leak. Instead, a leak in the vacuum control circuit will send all air flow to the defroster outlets. This condition may occur during acceleration (slow leak), may exist at all times (large leak) and may happen only when certain specific functions are selected, indicating a leak in that portion of the circuit. With engine running and heater blower motor switch on high, check system airflow in each A/C control position to determine which position(s) have incorrect air flow. Refer to EATC Manual Override Vacuum Application Chart for correct system air flow.

Is airflow only from the defroster outlets for all positions? GO to A2. GO to A12. A2 CHECK VACUUM SUPPLY HOSE Check vacuum supply hose to be sure it is connected to both the engine manifold and vacuum check valve. Is hose disconnected? RECONNECT hose. GO to A1. GO to A3. A3 LEAK CHECK VACUUM SUPPLY HOSE NOTE: The vacuum hoses used in the passenger compartment control circuit are constructed from PVC plastic material. The vacuum hoses used in the engine compartment are constructed of Hytrel. Because of the materials used, the vacuum hoses should never be pinched off during diagnosis to locate a leak. Use Rotunda Vacuum Tester 014-R1054 or equivalent to locate vacuum leaks. A wood golf tee can be used as a plug when it is necessary to plug one end of a vacuum hose for leak test purposes. Disconnect vacuum supply hose from engine manifold fitting and from A/C vacuum check valve. Plug one end of hose and leak test with vacuum pump. Does hose leak? SERVICE vacuum hose. GO to A1. GO to A4. A4 CHECK SUPPLY HOSE FOR BLOCKAGE Disconnect BLACK supply hose from A/C vacuum check valve. Connect vacuum tester to supply hose and operate tester as if pulling a vacuum. If tester can pull a vacuum, hose is plugged. If tester pulls a partial vacuum, hose is restricted. Is hose plugged or restricted? REPLACE supply hose. GO to A1. GO to A5. A5 CHECK VACUUM CHECK VALVE Check A/C vacuum check valve for correct installation by removing the reservoir hose and the control assembly source hose (one at a time) from A/C vacuum check valve and check for vacuum. Engine must be running for this test. Is vacuum available at both check valve ports? RECONNECT both hoses. GO to A6. REPLACE A/C vacuum check valve. GO to A1. A6 LEAK TEST VACUUM CHECK VALVE Check vacuum tester and hoses for leakage. Remove A/C vacuum check valve from vehicle. Connect two hoses and a Tee fitting to outlet ports of A/C vacuum check valve. Connect Rotunda Vacuum Tester 014-R1054 or equivalent to Tee fitting. Pump 51 kpa (15 inches Hg) vacuum on A/C vacuum check valve and observe gauge reading. Does check valve lose more than 3.37 kpa (1 inch Hg) vacuum in one minute? REPLACE A/C vacuum check valve. GO to A1. REINSTALL A/C vacuum check valve and GO to A7.

A7 CHECK VACUUM RESERVOIR Connect Rotunda Vacuum Tester 014-R1054 or equivalent to A/C vacuum reservoir tank and bracket and leak test reservoir. Reservoir must hold vacuum. Does reservoir leak? REPLACE A/C vacuum reservoir tank and bracket. GO to A1. CONNECT hose to A/C vacuum reservoir tank and bracket. GO to A. A CHECK SUPPLY HOSE Remove climate control assembly. Refer to Section 12-03A. Disconnect and plug BLACK supply hose at A/C control. Disconnect other end of supply hose from A/C control and leak test hose with vacuum tester. Does supply hose leak? SERVICE hose. GO to A1. REMOVE plug and RECONNECT vacuum hoses. GO to A9. A9 CHECK CONTROL ASSEMBLY Disconnect vacuum harness at in-line multiple connector near A/C control. Plug all vacuum hoses except BLACK. Connect vacuum tester to BLACK hose. Select each function position, apply 51 kpa (15 inches Hg) vacuum and check for vacuum drop. Drop should not exceed 3.37 kpa (1 inch Hg) vacuum per minute for any function position. Does drop exceed 3.37 kpa (1 inch Hg) vacuum per minute? NOTE function positions where vacuum drops. GO to A10. GO to A14. A10 LEAK TEST CONTROL ASSEMBLY Remove vacuum harness from A/C control. Connect vacuum tester to control supply port and plug control port that indicated a leak in Step A9. Select function positions noted in Step A9 and apply 51 kpa (15 inches Hg) vacuum after selecting each position. Vacuum drop should not exceed 1.6 kpa (1/2 inch Hg) per minute. Does vacuum drop exceed 1.6 kpa (1/2 inch Hg) in one minute? REPLACE A/C control. GO to A1. GO to A11. A11 LEAK TEST JUMPER VACUUM HARNESS Plug one end of vacuum hose that indicated a leak in Step A9. Apply 51 kpa (15 inches Hg) vacuum to hose and observe vacuum gauge. Vacuum should not drop. Does vacuum drop? SERVICE vacuum jumper harness. GO to A1. CHECK connection of vacuum harness to A/C control for leak. SERVICE vacuum jumper harness. GO to A1. A12 EVALUATE SYSTEM AIR FLOW Repeat Step A1. Is the airflow in Step A1 correct for each function position? GO to A13. GO to A14. A13 ISOLATE LEAKING VACUUM CIRCUIT Repeat Step A1 and accelerate engine speed for each function position. Does airflow go to defrost during acceleration? GO to A1. GO to A14. A14 REVIEW VEHICLE HISTORY Check history of operation with owner. Did system function properly prior to this complaint?

GO to A17. GO to A15. A15 CHECK VACUUM HOSES Check each vacuum hose to be sure it is not plugged. Is a hose plugged? REPLACE vacuum hose. GO to A1. GO to A16. A16 CHECK VACUUM HARNESS Compare vacuum hose colors in each vacuum harness to the vacuum schematic. Do the hose colors agree with the schematics? GO to A17. REPLACE vacuum harness. GO to A1. A17 CHECK VACUUM CIRCUIT Check vacuum circuit for pinched or kinked vacuum hose. Is hose pinched or kinked? SERVICE vacuum hose. GO to A1. GO to A1. A1 CHECK VACUUM CIRCUIT CONNECTIONS Check each vacuum hose connection to determine if it is partially connected or disconnected. Is a vacuum hose connection disconnected or partially connected? RECONNECT hose. GO to A1. GO to A19. A19 CHECK VACUUM HOSE NOTE: Refer to Section 12-03A to access vacuum control motors. Disconnect both ends of vacuum hose in suspected circuit. Plug one end and leak test with vacuum tester. Does vacuum hose leak? SERVICE hose. GO to A1. GO to A20. A20 CHECK VACUUM CONTROL MOTOR NOTE: Refer to Section 12-03A to access vacuum control motors. Check vacuum motor for leaks with vacuum tester. Does motor hold vacuum? GO to A21. REPLACE vacuum control motor. GO to A1. A21 CHECK VACUUM CONTROL MOTOR INSTALLATION NOTE: Refer to Section 12-03A to access vacuum control motors. Check attachment of vacuum motor arm to damper door. Is vacuum control motor arm attached to door or door crank arm? CHECK for binding or damaged damper door. SERVICE or REPLACE damper door. GO to A1. CONNECT vacuum control motor arm to door and check operation. GO to A1.

PINPOINT TEST B: INSUFFICIENT, ERRATIC OR NO HEAT B1 CHECK FOR PROPER ENGINE COOLANT LEVEL Check engine coolant hot and cold. Is engine coolant at proper level (hot/cold) on radiator coolant recovery reservoir GO to B2. GO to B3. B2 CHECK FOR HOT WATER TO HEATER CORE INLET HOSE Start engine and allow to reach normal operating temperature. Feel heater core inlet hose. Is the heater inlet hose hot? GO to B4. GO to Section 03-03. B3 CHECK COOLANT SYSTEM INCLUDING RADIATOR CAP FOR LEAKS Fill coolant system to specified level. Pressure check coolant system using Rotunda Radiator Pressure Tester 014-R1069 or equivalent. It is not necessary to check components separately at this time. Does coolant system (including radiator cap) hold pressure? GO to B4. SERVICE engine cooling system. REFER to Section 03-03. B4 CHECK HEATER CORE OUTLET HOSE FOR HOT WATER Engine operating and at normal operating temperature. Feel heater core outlet hose. Is heater core outlet hose cool or cold? SERVICE heater core for plug or partial plug. REFER to Component Tests. REFER to Section 12-03A for A/C electronic blend door actuator inoperative, intermittent or improper operation. PINPOINT TEST C: ENGINE COOLING FAN DOES NOT OPERATE WHEN A/C IS ACTIVATED C1 CHECK FUSE Remove cooling fan Fuse P (30A) from power distribution box. Check fuse resistance with ohmmeter. Is fuse OK? GO to C5. GO to C2. C2 CHECK FOR SHORT IN VOLTAGE SUPPLY TO RELAY Remove cooling fan relay. Using an ohmmeter connected to a known good ground, connect second lead to cooling fan relay connector Pin C12, Circuit 37 (Y). Is resistance 10,000 ohms or more? GO to C3. SERVICE Circuit 37 (Y) for short to ground. RESTORE vehicle. RETEST system. C3 CHECK FOR SHORT IN VOLTAGE SUPPLY TO COOLING FAN MOTOR Disconnect cooling fan motor connector C132. Using an ohmmeter connected to a known good ground, connect second lead to cooling fan motor connector C132, Circuit 229 (R/O). Is resistance 10,000 ohms or more?

GO to C4. SERVICE Circuit 229 (R/O) for short to ground. RESTORE vehicle. RETEST system. C4 CHECK COOLING FAN MOTOR OPERATION Reconnect cooling fan motor connector C132. Install good cooling fan Fuse P (30A). Connect a jumper wire between Pin C12, Circuit 37 (Y) and Pin C12, Circuit 229 (R/O) of the cooling fan relay connector. Does fuse open? REPLACE cooling fan motor. RESTORE vehicle. RETEST system. CHECK circuit for intermittent short to ground. RESTORE vehicle. RETEST system. C5 CHECK FAN OPERATION WITH RELAY BYPASS Install good cooling fan Fuse P (30A). Remove cooling fan relay. Connect a jumper wire between Pin C12, Circuit 37 (Y) and Pin C12, Circuit 229 (R/O) of the cooling fan relay connector. Does cooling fan motor run? GO to C9. GO to C6. C6 CHECK VOLTAGE SUPPLY TO COOLING FAN MOTOR Disconnect cooling fan motor connector C132. Using a voltmeter connected to a known good ground, check for B+ at cooling fan motor connector C132, Circuit 229 (R/O). Is there B+? GO to C. GO to C7. C7 CHECK VOLTAGE SUPPLY TO COOLING FAN RELAY Using a voltmeter connected to a known good ground, check for B+ at cooling fan relay connector Pin C12, Circuit 37 (Y). Is there B+? SERVICE Circuit 229 (R/O) for open circuit. RESTORE vehicle. RETEST system. SERVICE Circuit 37 (Y) for open circuit. RESTORE vehicle. RETEST system. C CHECK GROUND CIRCUIT Using an ohmmeter connected to a known good ground, connect second lead to cooling fan motor connector C132, Circuit 57 (BK). Is resistance 5 ohms or less? REPLACE cooling fan motor. RESTORE vehicle. RETEST system. SERVICE Circuit 57 (BK) for open circuit. RESTORE vehicle. RETEST system. C9 CHECK FOR FAN-ON PCM SIGNAL Using an ohmmeter connected to a known good ground, connect second lead to cooling fan relay connector Pin C12, Circuit 22 (DB). Start engine and select MAX A/C. Resistance should drop to 5 ohms or less within 30 seconds. Is resistance 5 ohms or less? TURN OFF engine. GO to C10. TURN OFF engine. GO to C11. C10 CHECK VOLTAGE FROM PCM POWER RELAY Turn ignition switch to RUN. Using a voltmeter connected to a known good ground, check for B+ at cooling fan relay connector Pin C12, Circuit 361 (R). Is there B+? REPLACE cooling fan relay. RESTORE vehicle. RETEST system. SERVICE Circuit 361 (R) for open circuit. RESTORE vehicle. RETEST system.

C11 CHECK FAN-ON PCM SIGNAL CIRCUIT Using an ohmmeter, check resistance of Circuit 22 (DB) between cooling fan relay connector Pin C12 and PCM connector Pin C15. Is resistance 5 ohms or less? REFER to Powertrain Control/Emissions Diagnosis Manual for WOT A/C cutout diagnosis. SERVICE Circuit 22 (DB) for open circuit. RESTORE vehicle. RETEST system. Component Tests Heater Core WARNING: CARBON MONOXIDE IS COLORLESS, ODORLESS AND DANGEROUS. IF IT IS NECESSARY TO OPERATE THE ENGINE WITH THE VEHICLE IN A CLOSED AREA SUCH AS A GARAGE, ALWAYS USE AN EXHAUST COLLECTOR TO VENT THE EXHAUST GASES OUTSIDE THE CLOSED AREA. The heater core is an all-aluminum core which has two rows of flat tubes to maximize engine coolant flow. It is located in the A/C evaporator housing in the passenger compartment under the instrument panel (04320). 1. NOTE: Testing of returned heater cores reveals that a large percentage of heater cores are good and should not have been replaced. If a heater core leak is suspected, it should be tested as described in the Plugged Heater Core procedures before removing the heater core. Perform a system inspection by checking the heater system thoroughly as follows: Inspect for visible evidence of coolant leakage at the heater water hose to heater core attachments. A coolant leak at the heater water hose (1472) could follow the heater core tube to the heater core and appear as a leak in the heater core. 2. Check the system for loose or overtightened heater water hose clamps. The clamps should be tightened to 1.7-2.4 Nm (15-21 lb-in). 3. If leakage is found and the heater water hose clamps are over-tightened, replace the clamp and tighten to the proper level. An over-tightened clamp can cause leakage at the heater water hose connection and damage the heater core tube. Plugged Heater Core Check to see that the engine coolant is at the proper level. Start the engine and turn on the heater. When the engine coolant reaches operating temperature, feel the heater core outlet hose to see if it is hot. If it is not hot, the heater core may have an air pocket or may be plugged, or the thermostat is not working properly. Pressure Test Use Rotunda Radiator Pressure Tester 014-R1069 or equivalent to perform pressure test. Item Part Number Description 1 014-R1069 Rotunda Radiator Pressure Tester 2 BT-7422-A Adapter (Part of 014-R1069) 3 BT-7422-B Plug (Part of 014-R1069) 4 27 Hose Clamp (4 Req'd) 5 Heater Hose 101 mm (4 Inches) Long 1. NOTE: Due to space limitations, a bench test may be necessary for pressure testing. Drain the coolant from the cooling system. Refer to Section 03-03.

2. Disconnect the heater water hoses from the heater core tubes. 3. Install a short piece of heater water hose, approximately 101 mm (4 inches) long on each heater core tube. 4. Fill the heater core and heater water hoses with water and install Plug BT-7422-B and adapter BT-7422-A from Rotunda Radiator Pressure Tester 014-R1069 or equivalent in the heater water hose ends. Secure the heater water hoses, plug and adapter with hose clamps (27). 5. Attach the pump and gauge assembly from Rotunda Radiator Pressure Tester 014-R1069 or equivalent to the adapter. 6. Close the bleed valve at the base of the gauge and pump 241 kpa (35 psi) of air pressure into the heater core. 7. Observe the pressure gauge for a minimum of three minutes. The pressure should not drop.. If the pressure does not drop, no leaks are indicated. 9. If the pressure drops, check the heater water hose connections to the core tubes for leaks. If the heater water hoses do not leak, remove the heater core from the vehicle and perform bench test as described. Bench Test Use Rotunda Radiator Pressure Tester 014-R1069 or equivalent to perform bench test. 1. Drain all coolant from the heater core. 2. Remove heater core from A/C evaporator housing. Refer to Section 12-03A. 3. Connect the 101 mm (4 inch) test heater water hoses with plug and adapter to the core tubes. Then connect Rotunda Radiator Pressure Tester 014-R1069 or equivalent to the adapter. 4. Apply 241 kpa (35 psi) of air pressure to the heater core. Submerge the heater core in water. 5. If a leak is observed, service or replace the heater core (as necessary). 6. Install heater core into A/C evaporator housing (1950). Refer to Section 12-03A.