A2L Refrigerants and the R-410A Transition: A Tech’s Guide

Rules as of October 20, 2026. Dates in this area have changed more than once; check the sources before relying on one.

What A2L means

ASHRAE Standard 34 rates refrigerants with a letter for toxicity (A lower, B higher) and a number for flammability, from 1 (no flame propagation) through 2L and 2 to 3 (highly flammable). A2L means lower toxicity and lower flammability: it can burn, but slowly, at a burning velocity of 10 cm/s or less, and it is harder to ignite than a hydrocarbon.

Swipe the table sideways to see every column.

GWP values: IPCC AR4, the basis used by the AIM Act.

Why R-410A is leaving new equipment

Two parts of the AIM Act push in the same direction. The phasedown cuts HFC production and imports in steps: 40% below the baseline from 2024, 70% from 2029 and 85% from 2036. And EPA's Technology Transitions rule (2023) requires new residential and light commercial AC and heat pump systems manufactured or imported from January 1, 2025 to use a refrigerant with a GWP below 700. R-410A, at 2,088, doesn't qualify; R-454B and R-32 do.

What changed in 2026

Under the original rule, split systems built from components made before 2025 had to be installed by January 1, 2026. In May 2026, EPA finalized a reconsideration of the rule, effective July 27, 2026, that removed that installation deadline: residential and light commercial split systems built from R-410A components manufactured or imported before January 1, 2025 can still be installed until the stock runs out.

• Unchanged: new residential R-410A equipment can't be manufactured or imported, so that stock only shrinks.
• VRF systems keep their own date: components made before January 1, 2026 can be installed until January 1, 2027.
• State rules can be stricter. New York, for example, has its own deadlines; check yours.

Servicing R-410A systems

Existing R-410A systems can be serviced and recharged with R-410A, and will be for years. As the phasedown tightens, expect R-410A to cost more and reclaimed R-410A to matter more, which makes careful recovery worth money as well as being the law. What you can't do is put an A2L into an R-410A system: A2Ls are approved only in new equipment designed and listed for them.

On the job with A2Ls

• Tools: recovery machines, vacuum pumps and leak detectors must be rated for A2L refrigerants, with sealed or spark-free electrical parts.
• Cylinders: R-454B and R-32 cylinders have left-hand threaded valves and a red marking, so standard hoses need an adapter. Recovery cylinders must be rated for the refrigerant too.
• Ignition sources: keep flames, sparks and hot surfaces away from an open circuit and ventilate the area. Recover the charge and purge with nitrogen before you braze.
• Leak sensors: many A2L systems include a refrigerant sensor that runs the indoor blower to disperse a leak. Don't bypass it; test it the way the manufacturer says.
• Charging: R-454B is a blend, so it leaves the cylinder as liquid; R-32 is a single component.

What the EPA 608 exam asks

Expect the safety classes (what A1, A2L and A3 mean), why A2L tools and recovery equipment must be rated for flammable refrigerants, and the AIM Act basics. The Core exam guide covers the safety and regulations sections, and the AIM Act leak repair guide covers the 2026 leak rules. The EPA 608 Exam Prep app includes A2L and AIM Act questions, plus a Toolbox with a pressure-temperature chart for R-454B, R-32 and R-410A.