R-134a is the default refrigerant for all automotive applications. If you own a car between 1994 and 2015 chances are that it takes R-134a. 134a is classified as an HFC refrigerant and does not contain Chlorine.
Just as R-22 was phased out residential and commercial units R-12 was phased out of the automotive market. R-134A is it’s replacement. R-134A has exploded in use over the last ten years with most all new vehicles being R-134A only.
R-134a’s peak may be waning over the next few years due to it’s high global warming potential. 134a has already been banned in the European Union and there are steps being taken to have it banned in America as well as to have it added to the Montreal Protocol. HFO refrigerants, mainly 1234YF, will be the primary replacement when 134a is gone.