Over the years I’ve observed a trend in customers: On one magical day at the beginning of every summer, when the temperature first nears 88°F and the humidity reaches 70 percent or more, a number of sweaty women with a broken air conditioner, two kids in tow (the youngest in diapers) and a paycheck in hand, show up at my shop - most within hours of each other. These dear ladies are not about to go through the summer with a broken air conditioner and hot and irritated children. Their comfort level is just as they claim: “so hot that they are going to die.” I often joke with such customers about losing friends to the heat every summer when I was a boy. To that they reply, “shut up Phil and fix my car.”

Air conditioning is a standard feature on most automobiles, rarely an option today. I remember my family’s first car with air conditioning, a blue 1955 Chevy. My father complained that he never thought he would spend so much money on a car, a mere $2,000 back then!

The cooling systems used in automobiles during the last 10 years are simpler, more accurate and easier to diagnose and repair than the one on that ’55 Chevy. However, like everything else today, there are environmental and financial considerations regarding the maintenance and continued use of existing systems.

Convert to r134aThe controversy over the environmental issues of R-12, (dichlorodifluoromethane, or CCl2Fl2), has been in the news lately. Whether or not it actually destroys the ozone layer is not discussed in this article. There is, however, a ready supply of R-12, and there will be for quite some time. It is not illegal to manufacture this refrigerant, but it is illegal for an unlicensed person to purchase or handle it. This is a fair law, applied in a similar sense for those who handle dynamite. Many concerned about the environment consider R-12 and R-22 to be equally dangerous.

The best way to repair a car with an R-12 system - on most vehicles manufactured before 1994 - is to repair the problem and have a certified technician refill the system with R-12. The prohibitive factor in this repair is the high cost of R-12. A 30-pound cylinder of R-12 once cost $25. Today it costs approximately $800. The average repair job uses about 3½ pounds of R-12, with a retail value of $125. The reason for the price increase is the environmental taxes applied to inhibit its use and promote the auto industry’s conversion to R-134a.

Those wishing to upgrade to the less expensive and environmentally safer R-134a can watch their savings be consumed by the cost of conversion. Unless the technician is extremely knowledgeable and fastidious in his conversion efforts, system failures are likely to occur. This refrigerant works well, but does not possess the thermal transfer capacity of R-12. Older cars, with their smaller condensers and evaporators, may not be cool enough in high-demand situations.

Lubricant Compatibility
In my opinion, if you frequently sit in gridlock traffic, you won’t be satisfied with the R-134a, especially if your R-12 system wasn’t performing satisfactorily before. There are physical as well as chemical challenges with this conversion. It is not as simple as buying a kit from the local auto parts store and installing the R-134a into the empty R-12 system.

Why? R-134a is not compatible with the 30W mineral oil used with R-12 systems. It must be thoroughly flushed and cleaned from the system; I cannot emphasize this enough. This is a difficult task. Either PAG (polyalkylene glycol) synthetic or AB (alkaloid benzyne) oils used with R-134a react violently with the chlorine residues from the R-12 oils. Premature compressor failure typically results.

Seal Compatibility
Conversion must also involve changing the seals on all hose fittings, front compressor seal, and in general, any rubber piece that the R-134a will contact. The hoses must also be changed, or they will begin to leak.

The question remains, should you replace the coolant in an R-12 system or convert to R-134a? I advise my customers to convert only if there is a major failure of the air-conditioning system, such as compressor failure. When the compressor fails, it must be replaced along with the filter/drier (accumulator). Add this to the expense of a new set of hoses and you have a good conversion job for about the same price as an R-12 fill-up. Done properly, the conversion is a wise decision for financial and environmental reasons.

There are aftermarket products which are R-134a mixed with a chemical that makes it only slightly less corrosive when introduced into unpurged R-12 systems. Some contain butane or propane and are potentially dangerous. The condenser in a car’s air-conditioning system is located directly behind the front grill of a vehicle. Imagine a quart of butane spewing from a ruptured condenser after a rear-end collision!

Don’t waste your money on the heavily advertised A/C inspections for $29.95. They serve only to get you into the shop where you can be sold more expensive, perhaps unnecessary repairs. The air conditioning either works or it doesn’t. If it doesn’t, have it repaired by a competent technician.

It has been a mild winter here in the South. I have a feeling I am going to see these ladies early this year.

Sidebar

Choosing Alternative Refrigerants for Motor Vehicle Air Conditioning
Scientists worldwide have concluded that CFC-12 and other chlorofluorocarbons deplete the ozone layer. As a result, more than 150 countries have signed a treaty, the Montreal Protocol, to protect the earth’s ozone layer. In the United States, the Protocol is implemented by the Clean Air Act, and regulations issued under the Act ended the production of CFC-12 for air-conditioning and refrigeration uses on December 31, 1995.

CFC-12 (also known by the trade name Freon) was widely used in air conditioners for automobiles and trucks for more than 30 years. While new vehicles no longer use CFC-12, most vehicles built before 1994 still require its use for servicing. As a result, 30 million cars or more may need conversions to use an alternative refrigerant should the air conditioning develop a leak after CFC-12 is no longer available.

Many service technicians believe that R-134a is only a temporary replacement for R-12, to be used until a drop-in replacement that cools well and does not require a retrofit becomes available. Current research indicates that no such replacement refrigerant exists. The worldwide automotive industry conducted extensive research and testing on many potential substitutes for R-12 before selecting R-134a. The EPA is not aware of any plans by the automakers to use any refrigerant in new vehicles other than R-134a.

R-134a is regarded as one of the safest refrigerants yet introduced, based on current toxicity data. The chemical industry’s Program for Alternative Fluorocarbon Toxicity Testing (PAFTT) tested R-134a in a full battery of laboratory animal toxicity studies. The results indicate that R-134a does not pose cancer or birth defects hazard.

OEM engineers and chemical manufacturers have examined the flammability and corrosivity of each potential R-12 substitute. Like CFC-12, R-134a is not flammable at ambient temperatures and atmospheric pressures. However, R-134a service equipment and vehicle air-conditioning systems should not be pressure tested or leak tested with compressed air. Some mixtures of air and R-134a have been shown to be combustible at elevated pressures. These mixtures may be potentially dangerous, causing injury or property damage. R-134a is not corrosive on standard steel, aluminum and copper samples.

The amount of R-134a charged into the system should normally be 80 to 90 percent of the amount of R-12 in the system. Most air-conditioning system manufacturers provide guidelines regarding the amount of R-134a to be used.

Source: United States Environmental Protection Agency (EPA), May 1, 2001
Web info: http://www.epa.gov