THE EVOLVING SERVICE PICTURE

Transcription

1 THE EVOLVING A/C SERVICE PICTURE BY PAUL WEISSLER R-134a has been with us for more than 10 years, and could continue as the U.S. refrigerant of choice for years to come, if updated tools and service techniques are properly implemented. J ust when you thought you had automotive a/c service figured out, it s ready to enter an entirely new era, with new equipment, new techniques and, in the next five years, apparently one or more new refrigerants. The chapters of the story have been unfolding each year at the convention and trade show of the Mobile Air Conditioning Society (MACS), and every time we look, the story seems to take some unexpected turns. Last year we discussed the issue of refrigerant conservation, the problems of recovery and accurate charging, and leak detection. Did we solve these problems for you? Maybe not. But while there s good progress to report, a number of new complications have entered the picture. R-134a still seems to have a solid future in this country, but increasing demand and environmental concerns have led to a lot of changes. The problems are mounting as fast as we can take notice of them, starting with the refrigerant itself. Buying Pure Refrigerant Because many third-world countries have been converting from R-12 to R- 134a, demand is up and new plants have been built in China. Questions have been raised about the purity of the refrigerant and the quality as delivered, particularly from China. So what are we talking about? While there are engineering standards for refrigerant purity, such as from the Airconditioning and Refrigeration Institute (ARI), as well as the recycling standards from the Society of Automotive Engineers (SAE), a poor production process will result in unacceptably high levels of certain impurities, which can affect a/c system materials and pressures, and possibly create blockages. If impurities are kept below 40 parts per million, they re not a concern. Also at issue is ingestion of moisture (should be under 10 ppm) and air (below 1%), both of which are postproduction concerns. You can t check for impurities or the presence of moisture with a refrigerant identifier; a lab test is required. And it takes a premium identifier to detect air of 2% and lower. However, if you periodically buy a jug of bargain R-134a from other than the most trusted sources (which we caution against, by the way), it s still a good idea to check it with an identifier. You might find out it isn t R-134a, but something else. One visual tipoff might be the color of the R-134a jug. It s supposed to be powder blue, not white (R-12) or green (R-22). But a MACS test of a jug at a military installation (and who has more elaborate purchasing systems than the 28 April 2006

2 military?) showed that a blue R-134a jug actually contained R-12. The Chinese refrigerant issue led two MACS trade show exhibitors to focus on the purity question. Contake Chemical Group U.S.A., a marketer of Chinese-made R-134a under the Bluestar brand, showed laboratory tests for a recent batch tested in China that revealed impurities at 38 ppm, just under the 40- ppm limit, low moisture (6 ppm) and low air content (.7%). Arctic Air posted signs at the show saying that although its jugs of R-134a come from China, the R-134a itself is produced in Japan and shipped to China where the jugs are made and filled. The U.S.-tested lab results showed they contained 4 ppm impurities, 7 ppm moisture and just.5% air. So stick with known suppliers, and double-check with a refrigerant identifier. Do No Harm Additives Show exhibitors also noted J2670, a new SAE standard for additives and flushing solvents that may be poured into the a/c refrigeration system. Although flushing solvents are removed with an air purge and by evaporation, there s no assurance that some solvent doesn t remain in the system s nooks and crannies. This SAE standard specifies tests only for compatibility the objective is to do no harm. It does not mean that the additive performs as advertised, or even does anything beneficial at all. Some of the additives sold for improved cooling have raised questions as to their effectiveness. But if they re certified to J2670, you re assured they won t cause deterioration inside the system, including to sealing materials. This standard does not have tests for trace dyes; they re covered by a separate standard (J2297), which includes tests for fluorescence. When you re buying additives or dyes, look for labeling on the container that tells you it meets the appropriate SAE standard, and look for a known brand. Compressor Oil Confusion At one time we thought we d get down to a single compressor oil for all R- 134a systems, but a number of things including the increasing popularity of gasoline/electric hybrids have helped muddy the picture. Indeed, General Motors once said a single PAG oil could be used for small additions on all its compressors except a few older designs. Now GM has gone even further, saying that its universal oil a PAG of Centistokes (Cst), ACDelco No / can be used in every system except the old A-6 and the Radial-4. In those, ACDelco No (a PAG in the April

3 The SAE work group on leak detection made many tests of existing electronic leak detectors, such as this false-trigger test with upholstery cleaner. As a result, the proposed new standard will require each detector manufacturer to specify which chemicals may cause its unit to false-trigger. Detectors would be required to resist falsetriggering from common automotive oil fumes. Photos: Paul Weissler This is a variable-displacement compressor that s being used in the new Dodge Caliber (the Neon s replacement). The compressor, which does not have a clutch, changes displacement according to a complex computer strategy that estimates cooling load. That s a more energy-efficient approach that s similar to ones being adopted by manufacturers worldwide to improve vehicle fuel economy. Illustration courtesy DaimlerChrysler range of Cst) is recommended. Unlike the days when all GM vehicles had Delphi compressors, today you also may find GM models with Denso, Sanden, Mitsubishi, Visteon and Zexel (a rotary vane type that was used on the Saturn L). So that gave GM some incentive to standardize where possible. Hey, what about the GM/Delphi V-5 and V-7 compressors, and those lightweight Delphi axial six-cylinder units (DA-6, H-6, HU-6, HT-6)? They seem to be covered by the new PAG universal oil. However, most shops that do a/c service these days stock at least two, maybe three PAGs: Cst and Cst, plus perhaps 100 Cst. So you may want to take this approach: For Delphi V-5, V-7, Radial-4, DA-6 and those lightweight H-series axial sixcylinder compressors, use the Cst oil if the compressor is old and noisy but still serviceable, to help reduce noise and vibration. If you re installing a brand-new compressor other than A-6 and Radial-4, you can use the Cst PAG. For other applications: Ford (all models) and Chrysler products with Denso compressors and Sandens that carry an SD-15 oil recommendation on the underhood label: Cst PAG. Chrysler products with Sanden seven-cylinder compressors that carry an SD-20 oil recommendation: 100 Cst PAG. Japanese and European cars with Sanden compressors (scrolls and seven-cylinder with an SD-15 spec): Cst PAG. European cars with Denso compressors: Cst PAG. That would seem to cover the waterfront, but it really doesn t. Denso, for example, makes Toyota-application You can t expect a refrigerant identifier to measure impurities, but some premium models (such as this Neutronics unit) can measure air, which you don t want to be paying for when you buy a jug of R-134a. In this case, the refrigerant is all R-134a, but 5% of the jug is filled with air. compressors that are not used by GM and that have requirements for special additives. The old R-12 DENSO TV rotary vane (Tercel/Paseo primarily), requires a synthetic oil labeled ND-7, not mineral oil (labeled ND-6 as used in other Toyota R-12 systems). Most Toyota/Denso systems with R- 134a use ND-8, or an equivalent ISO Cst PAG oil. However, the systems with the R-134a version of the TV rotary vane use ND-9, a specific PAG. And there s one more PAG: the Denso compressor in the RAV4 electric vehicle (very few produced and sold) uses another special PAG oil, ND-10. This oil obviously was chosen for the special operating cycle of air conditioning with the electric drive, and should not be used in any other electric, including all the Toyota hybrids. Do we really need all those special Denso oils for Toyota? It comes down to what Toyota certified. Generally, these oils are close to regular oil, but with special additives so the compressor gets through the Toyota endurance and smooth-performance tests it apparently just missed passing with ND-8. These special situations do occur. When it comes to the hybrids, there are even more choices, and the RAV4 30 April 2006

4 electric s ND-10 PAG oil is not one of them. Prius models up through 2003 use the same ND-8 (or ISO 46 equivalent) as in nonhybrids. However, 2004 and later models have an electricmotor-driven compressor, so the a/c can run with the engine off. This setup is also used on the Toyota Highlander hybrid and Lexus RX 400h, and requires a polyol ester oil. But isn t polyol ester the oil that was determined to be inferior to a good PAG? Yes, but with an electric motor in the compressor, the oil has to have high resistivity, so there is no current leakage from the 200-plus volt system (which could be a safety hazard for a technician). It takes an ester to provide that, and each one is a specific formulation. The same issue exists for the newest Honda Civic and Accord hybrids. Their compressor is a dual-drive both belt and (with the engine stopped) electric motor. So that compressor a Sanden design also requires a special ester, but it s not the same as the one used for the Denso. Another special oil isn t quite so special: The 2005 Toyota Tacoma trucks have a Delphi axial six-cylinder compressor that calls for a Delphi No. RL897 oil, which has a viscosity of ISO 61. Here again, this was a Delphi-certified oil for its factory-fill from its long-time oil supplier, and Toyota just picked up the Delphi oil recommendation. Right now, the vehicle is so new you won t be able to buy the stuff (even from a Toyota dealer), and we don t know when or if you ever will. GM is using a similar compressor with the Cst PAG, and we d say that oil should work. But if Toyota does decide to put RL897 into dealer stock, we ll let you know. The premium closed-end type PAG oils (referring to the chemical structure) widely used as original equipment originated in Japan and have been sold here exclusively by Apollo America. Now there s a competitive line from Castrol, marketed by Technical Chemical Co., that was introduced at the MACS trade show. PAG oil, which is recommended for engine-driven compressors, gets a No when it comes to electrically operated compressors used in some Toyota and Honda hybrids. And if you look underhood, you may even find a warning label that requires use of only a specific oil, which is a polyol ester. Photos courtesy American Honda Tools, Techniques & Parts Leak detection continues to be a popular topic at the MACS convention, particularly with the continuing trend toward smaller charges. We talked about a possible new SAE standard in last year s report. It has since been drafted, and now is going through the SAE review process. If it takes effect, it will require a new generation of ultra-sensitive electronic detectors with greater resistance to false-triggering, including in a fume-contaminated underhood environment. Although there was talk about specifying detectors that took static readings (point & shoot), the SAE work group decided to continue with the much tougher moving-probe test that simulates a technician at work. The current test requires 1 2-oz. leak detection with a probe moving past the leak at 1 to 2 in./sec., from a 1 4-in. distance. The proposed test in the draft version of the new standard requires detection of leaks down to 1 7 oz. (70% smaller), from a gap of 3 8-in. (a 50% increase) at 3 in./sec. (again, a 50% increase). However, don t try to get by with a cheap detector, while waiting for a nextgeneration unit to meet that standard in a year or so. MACS member shops with today s premium detectors report good results in finding leaks that other shops with the cheap detectors could not find. The good detector you buy now will continue to be useful even years from now. Also, follow the manufacturer s instructions, which say, basically: 1. maintain the detector; 2. adjust it carefully; 3. when the detector sounds, note the location and keep going until you ve checked the entire system. So what place in leak detection does trace dye have? Well, if the system already contains trace dye, using an ultraviolet light is a good way to look for a leak. Some manufacturers install it on the assembly line, although Chrysler has dropped it and Toyota doesn t recommend putting anything in the system besides refrigerant and oil. Or a technician may have installed it to find a previous leak. The trace dye manufacturers have been making their UV lamps far more compact, so they fit into tight quarters and, using 32 April 2006

5 Tracer Products new professional trace dye kit features its powerful Optimax flashlight-type LED ultraviolet lamp, six a/c dye capsules and, to the right of the case, two bottles of dye for other uses one for automotive oils and one for extended-life orange-dye coolants. Photo courtesy Tracer Products Bright Solutions introduced this new kit at the MACS trade show. It contains a subcompact flashlight-type LED lamp, dye capsules, syringe-type injectors and adapter hose, plus a spray bottle of dye clean-off solvent. Photo: Paul Weissler LEDs, produce much brighter lights. One dose of dye is enough. Adding extra shots of dye not only won t help, but because dye changes the viscosity of the oil, excessive use can adversely affect compressor life. Some smaller leaks such as one at the evaporator just won t always show up easily with today s electronic detectors. If you can gain access to the evaporator condensate drain, the UV light may illuminate a dye trace at the bottom of the drain tube. If there s no trace there, you can try inserting a borescope up the drain tube to inspect the evaporator core. The truth is that evaporators are tough to inspect because of their location. So before you just remove one because you can t find a leak elsewhere, at least disconnect the tubing connections under the hood, connect a vacuum pump and perform a vacuum decay test. This test isn t a sure thing, but it approximates the Ford warranty requirements. MACS recognizes the problem of evaporator leak detection, and proposals for new procedures have been advanced. There s nothing specific to report now, but we assure you the issue isn t being ignored. Compressor shaft seal leaks are another problem area, because they re usually significant only with the system running, when an electronic detector can t be used. Some technicians report good results by running the system with the electric fan disconnected to build up high-side pressures, then shutting it down and checking with an electronic detector around the clutch air gap and clutch hub nose. Trace dye also may help find shaft seal leaks. However, you may have to pull the clutch to find a dye trace in the shaft hub area. Don t forget to check all the compressor joints for leaks, not just the shaft seal. And if you find a number of small leaks on a system, replace all the seals involved. At the MACS show, Santech featured packs to make sure you have all needed seals. The Santech line also has special packs if This UView kit, which was also shown at the MACS trade show, contains its Spotgun Jr. caulking-cartridge-type dye injector and Phantome-Lite thin, small flashlight-type LED lamp. Photo courtesy UView Ultraviolet Systems Checking for a leak from a compressor shaft seal is a tough proposition, but the best time to do it is right after engine shutoff. You can probe with an electronic detector at the compressor nose and at the bottom of the clutch at the air gap. Photo: Paul Weissler 34 April 2006

6 Santech Industries features a line of a/c system seals in convenient packs. Shown here on display at the MACS trade show is the company s line of individualmake seal kits. Santech also sells model-specific service valve kits. With plastic snaptogether couplings holding more refrigerant joints together, AirSept introduced its first kit at the MACS trade show. The top row of four are for snap-ring couplings, the center pair are for new Volkswagens (primarily the Touareg) and the bottom tool is for a Mercedes coupling. Photo:s Paul Weissler you find the leakage is at the service valves, as it often is. If you find a leaking O-ring at a refrigerant line joint, replacing it is not always simple. If it s a tubular fitting, just unthread it. If it s a spring-lock coupling, you surely have one of the simple plastic tools for it. But many manufacturers are using snaptogether plastic couplings to hold the joint, and these take special tools to open. Classic Tool Design markets a simple screwdriver-type tool for the couplings used by Toyota. At the MACS show, AirSept introduced a kit that includes tools for VW and Mercedes vehicles. AirSept also said it intends to gradually expand tools coverage for these couplings. Trying to pry open a coupling with a pick or other jury-rigged setup could break the coupling, which means a Do you have one in this size? call to the dealer. When you find and fix a leak with an electronic detector on a system without trace dye, it s a good idea to inject a dose as a finishing touch. That can give you a head start if the system develops a new leak later on. The European plan to phase out R- 134a starting in is just a few years off. The intent was to convert to carbon dioxide (CO 2), an obvious refrigerant (it s dry ice) that has the most benign possible global warming implications. However, using CO 2 requires an ultra-high-pressure system, a difficult and expensive engineering issue. So despite a large investment in CO 2 a/c, the governing body of the European Union (a consortium of most European countries) left room to allow use of alternative refrigerants with slightly higher global warming numbers. The known alternatives were flammable, and therefore were given little chance. DuPont and Honeywell, however, recently announced that they have developed and would produce safe new refrigerants that would meet the low global warming requirements. All this may get confusing, and you may wonder what you should be doing. Here s our best take on the situation: EUROPEAN PHASE-OUT OF R-134A Adopt the Las Vegas line and think, What happens in Europe stays in Europe for a long time anyway. The U.S. and the rest of the world are committed to tightening up R-134a systems and greatly improving their efficiency nothing about that has changed in the last year. The needed changes all have been identified, and some already being used are costeffective for both the vehicle makers and motorists. They ll pay for themselves in better fuel economy. Even the Europeans are adopting many of them, because they realize that a full changeover to another refrigerant may start as late as 2011 and not be finished until It s unlikely to matter to the U.S. what refrigerant Europe chooses to use, or even if it chooses to use more than one (the cost of CO 2 is a problem for economy cars, and Europe makes a lot of those). However, what you care about is what happens here. We d guess that even if CO 2 makes the grade, European vehicles exported to the U.S. (primarily premium models) might get R-134a systems installed here, or at least charged with refrigerant here. BMW, Mercedes-Benz and Audi may command premium prices that would allow CO 2 a/c systems, but the absence of CO 2 system service outside of dealerships would be a problem. If a low-cost DuPont, Honeywell or other alternative refrigerant is chosen, it still is unlikely to be used on cars sold here for many years. Environmentalists might push for it, but supplies would figure to be tight for years because the market would be uncertain beyond Europe. If a new refrigerant is a success in Europe, a gradual phase-in worldwide might follow. What we heard about these alternatives indicates that they d force a learning curve similar to our 1990s changeover from R-12 to R-134a. Right now you have to deal with an increasing number of complexities regarding the R-134a systems you thought you knew well. 36 April 2006

7 The SAE work group on recovery/recycle/recharge equipment tested many vehicles and different machines (such as this ACR 2000) to determine the specifications for a new standard on refrigerant recovery and accurate recharging. Recovery & Recharging The issue of refrigerant recovery and accurate recharging, raised because of today s small-charge systems with their critical refrigerant levels, has led an SAE work group to draft a new standard for the equipment. As we pointed out last year, vehicle manufacturers specify charge accuracy in today s small systems to under 1 oz. This compares with margins of 3 oz. in late-1990s systems, up to 6 to 8 oz. or more in older systems. A related problem we also cited last year was that no one knew how much refrigerant is removed from the system by the recovery/recycle equipment. These factors explain why inaccurate charging is becoming a major cause of poor cooling performance. Since last year, the SAE work group has had research done that revealed that even very good equipment may not get out enough of the refrigerant. This is less of an issue when a system has leaked badly. However, more and more underhood and underdash repair jobs require recovery of the refrigerant so a/c components can be moved out of the way. In these cases, there may be a full charge in the system. Until new equipment is available (and the EPA is planning to eventually require use of only those machines that meet the next-generation standard), you can get better results with these steps: Don t try to recover refrigerant in low ambient temperatures. Tests run in the last year (with state-of-the-art equipment) indicate that only about 67% of refrigerant may be pulled out at 50 F with a single recovery procedure. At 70 F, the same machine would pull 84% with a single recovery. If the engine is warmed up and the accumulator heated, the recovery with two pulls may go up to over 93%. Moral: Warm up the engine, bring the car into the shop or wait for ambient temperatures to rise. And allow enough time for at least two pulls (preferably three), with a 15-minute wait in between. If you don t get out most of the refrigerant with the recovery machine, it will have to be vented with the vacuum pump (even then, only if you run it long enough) and that s counter to the EPA s campaign for refrigerant conservation tied to its anti-global-warming campaign. So you must remove about 95% of the refrigerant to help avoid overcharging. If you just short cut with a single pull of the recovery machine and leave in a lot of refrigerant, you could overcharge significantly, even if the correct amount of refrigerant is put back into the system. Accurate charging with today s equipment is problematical. As we said last year, the most accurate way to charge is with an accurate scale, following the equipment manufacturer s exact procedure. Although calibrated weights are ideal for checking scale accuracy, you can come close with new coins. Last year we suggested that 90 nickels plus two dimes added to the scale should increase weight by one pound. This year we ll also propose a total of 144 pennies to do the job. We repeat our annual warning: You won t get accurate results using a charging cylinder or sight glass, or charging according to pressure gauge readings or with small cans. Maintain the equipment, which includes changing the compressor oil (unless it s an oilless compressor, of course) and installing a new filter according to the recommended interval. And treat the equipment carefully. If it s been knocked around, it will give the poor results that lead to incorrect charging, poor cooling and shorter a/c compressor life. Visit to download a free copy of this article. Circle #23 April