What refrigerant has replaced CFC-12 in all automotive applications?

HFC-134a, also known as 1,1,1,2-tetrafluoroethane, has replaced CFC-12 (dichlorodifluoromethane) in automotive applications primarily due to its lower ozone depletion potential. CFC-12 was phased out under the Montreal Protocol because it contributes to ozone layer depletion, leading to significant environmental concerns.

HFC-134a does not contain chlorine, which is the component responsible for the destructive effect on the ozone layer. Its adoption in vehicles began in the early 1990s, and it became the standard refrigerant for automotive air conditioning systems. This transition was crucial for complying with environmental regulations aimed at protecting the earth's ozone layer while still providing effective cooling performance.

This choice highlights the importance of selecting refrigerants that are both effective in climate control and environmentally responsible. The other options listed either represent refrigerants that do not serve as direct replacements for CFC-12 in automotive use or are not suitable due to their environmental impact.