R12 is a type of refrigerant that was used in air conditioning systems of older cars sold in the United States. Today, R12 refrigerant is no longer available due to its environmental impact, so you may want to consider using one of the alternatives which are cheaper, legal to acquire and more environmentally friendly.
The direct alternative to R12 refrigerant is R134a refrigerant, which does not typically require you to modify your air conditioning system. Additionally, it's the only refrigerant that's approved as a replacement for R12 by the United States Environmental Protection Agency. Depending on the design of your car's air conditioning system, you may need to perform specific retrofitting procedures before you can begin using R134a as a replacement.
Non-EPA approved replacements for R12 refrigerant include several brands that contain a mixture of R134a, HCFC-142b or R22 refrigerant. The advantage of using a mixture is that you can sometimes avoid having to perform any retrofitting to get it to work with your existing AC system. The suppliers of mixture alternatives claim that they are refrigerants than R134a.
Three examples of mixture R12 alternatives are Free Zone, Freeze 12 and FRIGC. Free Zone is a combination of 79% R134a, 19% FCFC-142b and 2% lubricant. This is much different than the FRIGC compound, which is 59% R134a, 39% HCFC-124 and 2% butane.
There is also a group of illegal alternatives to R12 refrigerant that do not meet EPA standards. These illegal replacements include refrigerant mixtures of OZ-12, HC-12a and R-405a. It's important to avoid these because they can pollute the environment due to the fact that they contain excess hydrocarbons. Illegal refrigerants also pose as a fire risk if the vehicle is involved in a front-end collision and the air conditioning lines are ruptured, exposing the flammable gas to potential elements that could ignite it.
