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R-134a is the air conditioning refrigerant used in all new vehicles.

Quick History Lesson

Refrigerant is the gas that performs the actual cooling in your air conditioning system. For years, automobile air conditioning systems used a substance called CFC-12, also known by the names Freon and R-12. However, due to harmful effects on the Earth's ozone layer, production of R-12 was discontinued in 1995.

Subsequently, R-12 has been replaced by HFC-134a, also known as R-134a. Auto manufacturers began using R-134a in 1992. By 1994, all new-car air conditioning systems were manufactured with the new substance. While R-12 is no longer produced, it is still available in limited quantities.

If your car still uses R-12 and you need refrigerant, you have two options: continue using the R-12 refrigerant currently in your system, or convert your system to the newer R-134a refrigerant. Which option you choose will likely depend on how long you plan to keep your vehicle and how much a conversion costs.

Selling Your Car, But Need A/C for the Summer?

If your car uses R-12, and you plan on keeping the car for only a short time, then your best bet is to continue using R-12. Currently, R-12 costs between $30 and $50 per pound, with two to five pounds usually needed. This replacement isn't cheap, but it does cost less than converting your current system to accept R-134a, even though it costs around $8 to $9 per pound.

I'm Keeping My Car—Do I Convert?

Converting your system to accept R-134a can be pricey, sometimes costing up to $1,000. Depending on the vehicle, conversion involves replacing key components and fluids, not to mention minor parts like hoses, gaskets and O-rings.

But as AIS Master Technician Skip Christenson pointed out, "If an R-134a conversion costs a little more than an R-12 repair, it is probably wiser to have the conversion done, especially if you plan on keeping your vehicle for an extended period of time. At $8 to $9 per pound, compared to $30 to 50 for R-12, R-134a is much cheaper in the long run."