R-454B and R-32: What the New A2L Refrigerants Mean for Your AC Replacement

What changed

Under the EPA's Technology Transitions rule, as of January 1, 2025, most new residential and light commercial air conditioners and heat pumps must use a refrigerant with a global warming potential (GWP) of 700 or less. R-410A, the refrigerant in most systems installed over the past 15 years, is well above that limit and can no longer be used in new equipment.

The replacements most manufacturers chose are R-454B and R-32. Both are classified A2L, meaning lower toxicity and lower flammability, which is why newer equipment includes leak detection and why installers follow updated handling rules.

If your system still runs on R-410A

Nothing forces you to replace it. Systems manufactured before 2025 can still be serviced with R-410A. The practical issue is cost over time: as R-410A is phased down, refrigerant for leak repairs is likely to get more expensive, which tilts the repair-or-replace math for older systems with recurring leaks.

Why you can't just swap the outdoor unit

A2L outdoor units are designed to be matched with A2L-rated indoor coils or air handlers. Mixing an old R-410A coil with a new A2L condenser is not a like-for-like swap, so expect a replacement quote to include a new matched indoor coil or air handler. That also triggers HERS testing in California because the system counts as altered.

• Ask which refrigerant the proposed system uses.
• Ask for the AHRI certificate for the matched indoor and outdoor units.
• Ask whether the line set will be reused or replaced, and how it will be flushed and pressure-tested.