Since 1994, the most common refrigerant used in MVAC systems has been hydrofluorocarbon (HFC)-134a.Checked 2026-08-12
Air conditioning refrigerant (R-134a, R-1234yf)
The fluid that carries heat out of the cabin — and newer cars use a different one from older cars.
Also called: R-134a · R-1234yf · HFC-134a · HFO-1234yf · AC gas
What it means
Definition
The EPA states that since 1994, the most common refrigerant used in motor vehicle air conditioning systems has been HFC-134a. It also lists HFO-1234yf as an acceptable substitute for ozone depleting substances in these systems in new cars and other light-duty vehicles, with conditions for its safe use. The two are not interchangeable in one system, and the service fittings differ.
Why a buyer cares
What it changes
Which refrigerant a car takes determines what equipment a shop needs to service it. The under-hood label answers it in a second, and it is not something to assume from the car's age alone.
In practice
Where you meet it
On the under-hood A/C label, and on any recharge or A/C diagnostic invoice.
Two things that look alike
Not the same as
The compressor and condenser are parts; the refrigerant is what moves through them.
Read next
Related terms
Where it shows up
Related problem files
Where this comes from
Sources
EPA is listing HFO-1234yf as an acceptable substitute for ozone depleting substances (ODS) in motor vehicle air conditioning (MVAC) systems in new cars and other light duty-vehiclesChecked 2026-08-12
Which model years each maker switched over was not sourced and is not claimed.