What refrigerant has largely replaced R-12 in MVAC systems?

R-134a is the refrigerant that has largely replaced R-12 in mobile vehicle air conditioning (MVAC) systems. This replacement is primarily due to environmental regulations aimed at reducing the release of ozone-depleting substances. R-12, also known as dichlorodifluoromethane, was phased out because it contributes to ozone depletion and has a high global warming potential.

R-134a, or 1,1,1,2-tetrafluoroethane, was chosen as a replacement because it has a much lower ozone depletion potential and is less harmful to the atmosphere. It is compatible with existing components in many MVAC systems and has similar thermodynamic properties, making it an effective alternative for maintaining vehicle comfort and efficiency.

Substitutes like R-22 and R-404A are typically used in residential and commercial air conditioning systems rather than MVAC systems, which do not commonly utilize these refrigerants. R-1234yf, while it is a more recent refrigerant that has been introduced as a replacement for R-134a in newer vehicles due to its lower global warming potential, it has not yet replaced R-12 on a large scale. Thus, for the context of replacing R-12