A2L Is Here. EPA Still Lets Pre-2025 R-410A Inventory Sell Through.

The factory stopped making new R-410A residential and light-commercial air conditioners and heat pumps on January 1, 2025. That part of the AIM Act Technology Transitions rule did not reverse.

What changed in 2026 is the installation / sell-through clock on equipment that was already manufactured or imported before that date. Contractors were staring at a hard federal cutoff of January 1, 2026 for putting that legacy inventory on a pad. In May 2026 EPA published a final reconsideration rule that removes that federal installation deadline. Qualifying pre-2025 inventory can keep moving until it is gone. The rule took effect July 27, 2026.

This is not legal advice. Read the Federal Register notice and ask your AHJ. New York kept a state backstop. California cities will not all say the same thing on Monday morning.

What A2L actually means

ASHRAE safety group A2L means lower toxicity and mild flammability. The two refrigerants you are seeing on new residential and light-commercial splits are mostly:

• R-32
• R-454B

Both sit under the federal GWP 700 ceiling that applies to new equipment in this subsector. R-410A does not (its GWP is roughly 2,000). That is why the new boxes on the truck say A2L and the old ones do not.

Mildly flammable is not “propane.” It is also not “A1 forever, ignore the listing.” The listing (UL/CSA 60335-2-40), the manufacturer’s charge limits, minimum room area, refrigerant detection systems where required, markings, and ignition-source rules are the job. California’s path is the 2025 California Mechanical Code (Title 24 Part 4), Chapter 11, with ASHRAE 15-2022 / 15.2-2022 behind a lot of those numbers — not IRC M1411.2. SFM intervening proposal may adopt ASHRAE 15-2024 effective about July 1, 2027 if approved. We keep a jurisdiction-ready A2L HVAC System Affidavit on the Checklists tab for exactly that walk-through.

The dates that matter (federal)

New complete R-410A systems are not coming back off the line. Components labeled for servicing existing equipment only are a different bucket. Do not mix “I can still hang a 2024 outdoor unit from stock” with “I can assemble a brand-new R-410A system from post-2025 condensing units.”

Packaged products that do not need field assembly (window units and similar) have their own sell-by rules under the Technology Transitions framework — often a multi-year sell-through after the manufacture date, with a backstop no later than January 1, 2028 for some categories. Split systems are the inventory fight most California change-out crews care about.

What this does not change

• Title 24 / HERS/ECC. Low-GWP refrigerant does not erase the CF1R, the load path the city wants, or the CF3R tests that apply to the job.
• Existing R-410A systems. You can still service and recharge them. Virgin R-410A supply will tighten as the AIM phasedown bites; price is the market’s problem, not a code sunset on your homeowner’s ten-year-old condenser.
• State and local backstops. EPA removed a federal installation deadline. A state statute or local amendment can still be stricter. New York is the national example everyone cites. Call San Diego City, the County, Chula Vista, Oceanside — whoever stamps the permit.
• Flammability paperwork on A2L jobs. Sell-through of old R-410A stock does not teach your crew how to set an R-454B charge limit in a small bedroom. That is still CMC Chapter 11 and the listing.

Why EPA blinked

Builders order equipment months before the house is ready. Distributors were sitting on legal pre-2025 iron that would have become scrap on a calendar date. A2L refrigerant and compatible product also hit availability and cost bumps that the 2023 rule did not fully price in. ACCA and others asked for stranded-inventory relief. The May 2026 rule is that relief for residential and light-commercial AC/HP inventory that qualifies.

Industry groups are already in court over pieces of the broader reconsideration package. Watch the D.C. Circuit if you bet a warehouse on any part of the rule outside the inventory language. For the pad in San Diego County, the practical question is simpler: is this outdoor unit / matched system documented as manufactured or imported before January 1, 2025, and does my AHJ still allow it?

What we are telling contractors this week

1. Legacy R-410A — If it is still in distribution and the date codes / importer paperwork clear Jan 1, 2025, the federal installation cliff is gone. Confirm with the supply house and the AHJ before you promise the homeowner “R-410A forever.”
2. New equipment — Bid A2L (R-32 / R-454B) as the default. Budget listing, room-volume, RDS, and markings the way you already budget a disconnect.
3. Do not dual-path the paperwork — One CF1R, one refrigerant story. Mixing an A2L outdoor with an R-410A indoor (or the reverse) because “stock was weird” is how finals fail.
4. Use a checklist — Our A2L HVAC System Affidavit is built for 2025 CMC Chapter 11 / ASHRAE 15 language California actually uses.
5. HERS/ECC still shows up — Change-outs that need a CF3R still need a CF3R. Refrigerant class is not a free pass.

We do not hang the condenser. We write the Title 24 and we test the system. If your change-out just became an A2L / R-410A inventory argument at the counter, put us on the call so the CF1R and the mechanical submittal say the same thing.

Call 858-254-1189.

— Bruce Cheney, Anchors Aweigh Energy