R-12 Refrigerant is the original Refrigerant. At one point in time it was used for everything including home air conditioning units, automobiles, and refrigerators. It was invented by a partnership of DuPont and General Motors back in the 1920s and was being used as the primary type of Refrigerant for home units until the 1950s. In the 1950s the newer R-22 Refrigerant took over the home and refrigerator market. R-22 was easier on the compressors and didn’t’ require as big of pipes to flow through.
Even though R-12 lost the home market it was still THE Refrigerant to use in automobiles. In 1994 the Environmental Protection Agency mandated that all new vehicles use R-134A Refrigerant rather than the R-12 Refrigerant that was used for over seventy years. The EPA mandated this change due to the Chlorine found in the R-12 Refrigerant. Chlorine damages the O-Zone layer and due to the amount of the vehicles on the road there was significant damage being done to the O-Zone layer. The R-134A Refrigerant does not harm the O-Zone layer. (Although it does produce greenhouse gases which contribute to Global Warming.)
R-12 has been phased out for twenty years now. (1994-2014.) If you have a vehicle older than 1994 you have two choices. You can either retrofit your car so that it will be compatible with R-134A Refrigerant, or you can try to purchase some R-12 Refrigerant from a supplier or online. If you choose the latter be prepared to pay a hefty price. I’ve seen R-12 Refrigerant go from $500.00 a cylinder all the way up to $1,100.00 a cylinder. If it was me I would go the retrofitting route rather than purchasing. This allows you to use the common and less expensive R-134A Refrigerant and it also keeps you in compliance with EPA regulations. R-12 is strictly regulated by the government and if you were to accidentally vent some of the R-12 Refrigerant into the atmosphere you could face very hefty fines.
All in all R-12 is the dinosaur of Refrigerant. It’s going to be completely extinct here in the next ten to twenty years. But, it did serve a purpose as it was the first Refrigerant and provided cooling for the world for nearly a century.