AC Refrigerant Types: R-22, R-410A, R-32 and R-454B Compared

Three generations of home AC refrigerant

Residential air conditioning in the US has gone through three refrigerant generations in about 25 years, each driven by environmental rules rather than performance alone.

• R-22 (HCFC): the standard for decades. It damages the ozone layer, so it was phased out under the Montreal Protocol and the Clean Air Act.
• R-410A (HFC): ozone-safe and the standard for new systems from 2010 until 2025. Its drawback is a high global warming potential (GWP).
• A2L refrigerants (R-454B, R-32): lower-GWP replacements required in new equipment under the AIM Act from 2025. They are classed as mildly flammable.

The refrigerant in your system is printed on the outdoor unit's nameplate.

Comparison table: GWP and safety class

GWP compares the warming effect of 1 kg of gas with 1 kg of CO₂ over 100 years; the values above use the IPCC AR4 figures that US regulations reference. In the safety code, A means low toxicity; 1 is no flame propagation, 2L is lower flammability with a slow burning velocity, and 3 is highly flammable.

The R-22 phase-out

New air conditioners charged with R-22 could not be made after 2010, and since January 1, 2020, R-22 can no longer be produced or imported in the US. Existing systems can still be serviced with recovered and reclaimed R-22, but supply is limited and the price reflects it.

R-22 systems cannot be topped up with R-410A: the two run at very different pressures (compare them on our PT chart) and use different oils. Some "drop-in" replacement blends exist, but they usually require oil checks, give some capacity loss and should only be used by a technician following the blend maker's procedure. If an R-22 system has a major leak or compressor failure, replacement is usually the better use of money; see how long AC units last.

The 2025 AIM Act transition

The American Innovation and Manufacturing (AIM) Act of 2020 directs the EPA to cut US HFC production and consumption by 85% from baseline by 2036 and to restrict high-GWP refrigerants in new equipment. Under the EPA's Technology Transitions rule, new residential and light commercial air conditioners and heat pumps manufactured or imported from January 1, 2025 must use a refrigerant with a GWP below 700. A limited sell-through period applied to split-system components already built with R-410A.

What this means in practice:

• A working R-410A system can stay in service for its full life. Nothing requires you to replace it.
• R-410A remains available for repairs, though prices are expected to rise as allowances shrink.
• New systems use R-454B or R-32 with matched indoor coils, line sets checked for size and cleanliness, and A2L-rated components. You cannot mix an R-410A outdoor unit with an A2L indoor coil or vice versa.

What A2L means for safety and installation

A2L refrigerants can burn, but only at fairly high concentrations, they are hard to ignite and the flame spreads slowly. The safety standard UL 60335-2-40 and model codes manage the risk with charge limits based on room size, refrigerant leak detection sensors in many ducted systems, and mitigation that turns on the indoor blower to disperse a leak.

Do not try to braze, recover or vent any refrigerant yourself. EPA Section 608 certification is required to buy refrigerant for stationary systems and to open the system, and A2L work also needs spark-proof recovery equipment and tools rated for flammable refrigerants.

R-454B versus R-32

Both are mildly flammable and both perform close to R-410A. R-32 is a single component, so it has no temperature glide and can be charged as vapor or liquid; its higher discharge temperature has to be designed for. R-454B has a lower GWP and pressures a little below R-410A, which made it an easier fit for ducted equipment designs; as a zeotropic blend it has a small glide and must be charged as liquid. For a homeowner, the choice usually comes down to which brand and model you prefer, not the refrigerant. Efficiency is set by the equipment's SEER2 rating, not the gas.

Window, portable and small units

Many window and portable units use R-32 or R-290 (propane) in small, factory-sealed charges. These are not designed to be recharged in the field; a unit that has lost refrigerant generally needs replacement. Our guide to recharging a window AC explains why.

Frequently asked questions