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Once a year, air conditioning specialists from all over gather together at the annual Mobile Air Conditioning Society (MACS) convention and trade show. This one was held in Orlando, Florida and attracted approximately 2000 attendees and 240 exhibitors.

One key question that was addressed during the technical sessions was the current status of R12 refrigerant. When the production of R12 ended in this country back in January 1996, nobody knew for sure how long existing supplies of R12 would last, or how this would impact the air conditioning parts and service business. The general consensus was that R12 would run out within a few years. This would force a growing number of motorists to have their vehicles converted to R134a when their A/C system failed or needed major repairs.

Last year, the U.S. Environmental Protection Agency predicted that the remaining supplies of virgin R12 would run out by the end of the year. Their prediction was based on an estimated demand of about 19 million lbs. of R12 versus an estimated stockpile of about the same amount. So according to EPA figures, we have run out of R12.

The fact is R12 is still available through prices are high. Nobody knows for sure how much R12 is out there, but there does not appear to be any serious shortage at this time. The EPA says mandatory recovery and recycling has helped to extend the existing supply of R12, and last summers mild weather reduced the demand for refrigerant. But the EPA also admits that a lot of illegal R12 is still being smuggled into this country from offshore, namely Mexico.

According to the most recent MACS field survey of member shops, approximately 55 percent of the vehicles being serviced today still use R12 refrigerant. Only about 6 percent of the older vehicle population has been retrofitted to R134a, and less than one percent of these contain some type of blended refrigerant.


The EPA, U.S. Customs Service and Justice Department are continuing to investigate smuggling operations and have made a number of well-publicized arrests. Even so, there still seems to be a steady flow of bootleg R12 into this country. As long as there is a demand, it seems that somebody will provide a supply.

The EPA warns distributors and users alike to "know your sources." Some bootleg refrigerant is contaminated with other refrigerants such as R22 and/or flammable hydrocarbons (propane or butane).

Buying or using refrigerant from a questionable source can be risky business, not only because of possible contamination but because of possible legal consequences.

It is illegal to knowingly buy or possess illegal R12 that has been smuggled into the U.S. Not only will the illegal refrigerant be confiscated, the guilty party will also have to pay taxes on it as well as a fine and possible jail time. A number of individuals have already been fined hundreds of thousands of dollars for smuggling R12, and some are now serving time in federal prisons.


As long as R12 is still being produced anywhere in the world, the smuggling problem will not go away. Back in 1987, an international agreement called the Montreal Protocol called for the phase out of all ozone-depleting chemicals, which included a family of man-made chemicals called CFCs (chlorofluorocarbons). Among these were R12 refrigerant (which up to that point in time was used in all automotive A/C systems) and R22 (which was used in most stationary A/C equipment). The agreement called for a total ban on CFC production in all industrialized nations, but left a loophole open for developing nations by allowing them to continue producing and using CFCs.

At the time, nobody worried too much about the loophole because the United States and Europe accounted for most of the R12 that was being produced. But as the vehicle population continues to grow in developing nations, particularly Asia, the loophole may offset many of the gains we have accomplished by phasing out R12.

According to research by the Delphi Corporation, the world vehicle population is predicted to reach 1 billion by the year 2015 -- and 85 percent of these vehicles will be equipped with air conditioning. The biggest increase in vehicle usage is occurring in China and other parts of Asia. China's current vehicle population is only about 17 million vehicles (compared to 230 million for North America), but it is expected to double in the next five years. Even if these countries switch to R134a, which is "ozone-safe" and contains no ozone-damaging chlorine, R134a poses yet another environmental concern.

R134a is a "greenhouse" gas that contributes to global warming. Gases such as carbon dioxide, which occur naturally in the environment but are also produced as a byproduct of combustion, trap and hold heat in the atmosphere. Scientists say the level of CO2 has been gradually rising over the past century and seems to be accelerating at an ever faster pace. They blame it on the continued burning of fossil fuels, industrial activity, "slash-and-burn" agricultural practices in many Third World countries, and the destruction of rain forests (trees take carbon dioxide out of the atmosphere by using it to build plant fiber).

As the level of CO2 continues to rise, scientists fear that it is causing a gradual warming of the Earths average temperature. This, they say, will have devastating effects on the global climate and cause unpredictable changes in weather, agriculture and ocean currents. Some say it may even lead to a melting of the polar ice caps causing the oceans to flood coastal areas.

Fears over such dire predictions lead to a world summit in 1998 that called for a new international agreement to reduce man-made CO2 worldwide. The Kyoto Protocol, as it was called, has yet to be finalized. The U.S. has not signed it because it would call for more fuel efficient vehicles, the trading of "CO2 credits" between nations, and the possible development of a new class of refrigerants.

One pound of R134a that escapes into the atmosphere has the global warming equivalent of 1,300 lbs. of CO2. Consequently, every ounce of R134a refrigerant that leaks out of automotive A/C system adds up to a lot of global warming potential.

Delphi research estimates that the total lifetime emissions of a typical vehicle today is about 2.3 lbs. of refrigerant, which is the equivalent of about 3000 lbs. of CO2. This is based on normal leakage and recovering and recycling 75 percent of the original refrigerant.

If you multiply the rate of leakage times the exploding world population of vehicles equipped with air conditioning, it is easy to see that R134a can be a factor in the global warming issue. But in relation to all the other man-made sources of CO2, it is still almost noting, only about 0.14 percent of all man-made emissions.

Even so, some vehicle manufacturers are looking at new alternative refrigerants that would pose few if any environmental hazards. The Europeans are moving quickly to develop next generation A/C systems that use CO2 as a refrigerant instead of R12 or R134a.


Sometime next year, BMW and/or Mercedes may be the first vehicle manufacturer to offer a high pressure CO2 A/C system. These next generation A/C systems, which are currently undergoing field tests, use a variable displacement compressor and sophisticated electronic controls to circulate high pressure (1800 to 2200 psi) CO2 through a refrigeration loop to cool the vehicle. Tests conducted in the summer heat of Arizona have shown that these new CO2 systems actually cool better than today's best R134a systems. What's more, because CO2 is nontoxic, ozone-safe and is already present in the atmosphere, recovery and recycling will not be necessary. A system can be vented directly to the atmosphere, something which is now illegal with todays refrigerants.

The Europeans are also moving quickly to convert to 42 volt electrical systems. With higher operating voltages, it is possible to get rid of the belt-driven A/C compressor and use an electric compressor. Such a system can also be used with a fuel cell powered vehicle that runs on electricity and has no internal combustion engine. Fuel cell technology is advancing rapidly in Europe, and many experts predict that within the next 5 years vehicles powered by fuel cells will be in production.

Another new refrigeration system that is being developed is "secondary loop" cooling. With this approach, a hydrocarbon refrigerant is used to cool a liquid through an chiller. The cooled liquid then enters the passenger compartment and circulates through a heat exchanger to cool the air. The system requires an electric pump to circulate the liquid, which adds cost, and by isolating the flammable hydrocarbon refrigerant to the engine compartment, it overcomes the safety objections of using hydrocarbon refrigerants in automotive applications. It is currently illegal to use a flammable hydrocarbon as a refrigerant in a mobile automotive applications, but hydrocarbons are used in some semi-trailer refrigeration units.

Another change that is being made to reduce the impact of today's refrigerants on the environment is a new generation of refrigerant hose. Goodyear has developed a new type of "low permeation" barrier style hose. Their new "Galaxy 4890" hose has a chloroprene inner liner that reduces refrigerant seepage by 78 percent compared to current barrier style hoses, and also reduces moisture infiltration that can cause system contamination. Goodyear says their next goal is to develop a "zero" permeation hose that is flexible and allows no refrigerant seepage for the life of the vehicle.

automotive climate control system


Regardless of what type of refrigerant tomorrow's vehicles will use, today's automatic climate control systems continue to become more complex. The trend in recent years has been to add more features and more electronics. The availability of "dual-zone" A/C systems that provide separate controls for the driver and front passenger continue to multiply.

For 2001, Chrysler is offering the first "triple-zone" automatic climate control system in its minivans. The optional A/C system has separate controls for the driver, front passenger and rear passengers. The system uses infrared sensors front and rear to monitor the cabin temperature, and a new type of 2-wire electric motor to control all the blend air doors in the HVAC system. The system has 22 different control modules that communicate back and forth over a common bus network of multiplex wiring. So complicated is this new system that it can generate over 1000 different fault codes!

Mercedes also has a new dual-zone automatic climate control system in its C320 models that adds a few new twists. One is a compressor that has no clutch. The belt-driven variable compressor runs all the time and is controlled by a pulse width modulated signal that can vary its output from 2 to 100 percent according to the cooling load on the system. There is also a "smog sensor" that closes off the outside air inlet if it sniffs hydrocarbons or other bad odors. Ten electric motors are used to control the various blend doors in the HVAC system, and a sun sensor on the dash modifies A/C/ output to compensate for sun load. The engine cooling fan is also partially controlled by the HVAC system, and 15 different interior control modules are used to regulate cooling. To make matters worse, technicians cannot access the "enhanced" fault codes for the system without the official Mercedes scan tool. Aftermarket scan tools can only read the OBD2 "generic" codes.

The old manual cable and vacuum operated A/C systems are rapidly disappearing, though the Chrysler PT cruiser still has a manual system with cable controls for 2001.


One of the most controversial aspects of A/C service today is compressor lubricants. Because R134a is not compatible with mineral-based compressor oil, it requires a different type of lubricant. Virtually all OEMS today specify one of several different types of PAG oils for their compressors. PAG oils vary according to viscosity, with PAG 46, PAG 100 and PAG 150 being the three most popular blends. The type of PAG oil required depends on the design of the compressor. And because compressor failures are the leading cause of A/C system failures, it is important to use the correct type of lubricant. But technicians are often confused or misinformed about which type of lubricants they should use in various applications.

According to the MACS field study, 53 percent of technicians are using PAG oil with R134a, but 43 percent are using POE (polyester) oil in R134a systems

POE is a popular aftermarket lubricant because it is compatible with both R12 and R134a, making it a good choice for older vehicles that are being retrofitted to R134a. Even so, the "official" MACS and OEM recommendation is to use PAG oil only with R134a. For all newer R134a systems (most 1995 and up vehicles), use the type of PAG oil recommended by the vehicle manufacturer. PAG oil is not compatible with R12 and must not be used in older R12 systems.

Mineral-based compressor oil should only be used in older vehicles with R12. Mineral oil must never be used with R134a because the two will not mix. This will prevent the oil from circulating through the system and lead to compressor failure.

Most replacement compressors today are manufactured with seals that are compatible with both types of refrigerant. But some are shipped dry while others are prefilled with either PAG or POE oil. So installers must be careful to make sure they do not intermix oils or use the wrong type of oil for the application.

Click here to view PAG oil recommendations.

To minimize the risk of a repeat compressor failure, technicians should also do everything they can to protect the new compressor from contaminants. Compressor failures often throw a lot of debris into the condenser, but some of it can also blow back up the suction hose. For this reason, some manufacturers recommend flushing out the condenser and hoses, installing an inline filter to trap debris, and an inlet screen in the suction hose to protect the compressor.

Flushing is also a controversial subject because the vehicle manufacturers do not agree on which technique works best or even if it works at all. Ford approves flushing with VSL338 terpene-based solvent while GM says its okay to flush but only with R134a, no solvents. Chrysler and Toyota do not recommend flushing. If the system is contaminated and contains debris, Chrysler says it is safer to replace the condenser and hoses. Flushing may dislodge most of the debris in a serpentine flow condenser, but does not work very well in parallel flow condensers.

Parts proliferation continues to be an ongoing challenge for the aftermarket. Twenty years ago, there were half a dozen different basic compressor designs. Today the number has grown to over 1800 and will top 2000 before the end of this year!

Refrigerant contamination is another problem the industry faces. In 1997, the MACS field survey found 2.3 percent of A/C systems were contaminated with air, other refrigerants or hydrocarbons. In 2000, the number jumped to 5.3 percent. This underscores the need for shops to use refrigerant identifier equipment do check vehicles prior to servicing them. MACS says 71 percent of their member shops are now using an identifier to prevent cross-contamination.


The EPA is still in the process of revising its Section 609 SNAP rules, which includes a proposed ban on the sale of R134a to non-certified individuals. Like the ban on R12 sales to DIYers, the new rule would restrict the sale of R134a refrigerant to certified professionals only. The new rule may go into effect late this year or early next year.

The EPA is also reviewing a possible ban on disposable refrigerant cylinders. The concern here is the environmental impact of residual refrigerant that may be left in these cylinders when they are disposed of.

The EPA has a hotline (1-800-296-1996) to answer nontechnical questions about refrigerant laws. Technical information for shops is available at the website.

The EPA says is inspected about 400 shops last year, which resulted in 86 enforcement actions. Most of these were warnings but some were fined for various violations. The EPA says its current focus has shifted from getting A/C service shops certified to making sure they are doing retrofits correctly. Current retrofit regulations require recovery and recycling of any residual R12 refrigerant still in the vehicle, installing new service fittings, installing a high pressure cutout switch, and labeling the system to identify the type of refrigerant used.

The MACS field survey found that only about 62 percent of vehicles that have been retrofitted have been retrofitted correctly!

For complete details on retrofitting older R12 A/C systems to R134a, see R134a Retrofit Guide.

Finally, the California Bureau of Auto Repair announced its new A/C service rules for the 35,000 registered repair facilities in their state. The new A/C service rules require shops to have the proper equipment (recovery/recycling machine, gauge sets and a thermometer), to follow a 13-item inspection list when servicing A/C systems (checking for proper service ports, hose and seal leaks, etc.), and recording system high and low pressures, and the A/C outlet temperature on service invoices. The regulations do not specifically require leak repairs and allow the topping off of A/C systems provided they have been properly inspected.

More Air Conditioning Articles:

Air Conditioning Service Best Practices (Procedures a repair shop should follow when servicing your A/C system)

MACS Recommended A/C Service Procedures (PDF file - requires Adobe Acrobat Reader to view).

Air Conditioning Inspection Checklist

A/C Cooling Problem: Blows Warm Air Only No Cool Air

Troubleshooting Air Conditioning Problems

Troubleshoot Automatic Climate Control

Troubleshooting A/C Cooling Problems with Temperature

Cooling Fan (electric)

Cooling Fan Relay Problems

How To Recharge Your Car's Air Conditioner

Refrigerant Contamination

Alternative Refrigerants for R-12

New Automotive Refrigerants
Information about Retrofitting older vehicles with R-12 A/C systems to R-134a

A/C Compressor Failures

A/C Condenser Flushing

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