Short answerSince January 1, 2025, new residential split-system air conditioners and heat pumps must be manufactured with low-global-warming-potential A2L refrigerants, mainly R-454B and some R-32, instead of R-410A. A2L refrigerants are classified as mildly flammable, so new equipment includes leak-detection sensors and revised installation rules. Existing R-410A systems can still be serviced and recharged indefinitely.
The rule behind the change
The American Innovation and Manufacturing Act of 2020 directed the EPA to phase down hydrofluorocarbons, the refrigerant family that includes R-410A. R-410A does not harm the ozone layer, which is why it replaced R-22, but it has a global warming potential of roughly 2,088 times that of carbon dioxide. The EPA's Technology Transitions rule set a GWP ceiling of 700 for new residential air conditioning equipment and tied it to a manufacture date of January 1, 2025. Manufacturers responded by picking from a short list of lower-GWP options, and the two that won out for residential split systems were R-454B, with a GWP around 466, and R-32, with a GWP around 675.
Carrier, Bryant, Lennox, Trane, American Standard, Rheem, Ruud, York and most others standardized on R-454B. Daikin, Goodman and Amana went with R-32, which Daikin had been using in Asia and Europe for a decade. For a homeowner in Ann Arbor or Saline shopping for a replacement this year, that means nearly every quote you get will be for one of those two gases, and the difference between them matters less than the quality of the installation.
Why "mildly flammable" is the detail everyone asks about
R-410A is an A1 refrigerant: nontoxic and nonflammable. R-454B and R-32 are A2L: nontoxic, but capable of burning under a narrow set of conditions. The "L" stands for low burning velocity. These gases need a high concentration in air, a significant ignition energy, and a sustained source before they will ignite, and a flame front moves slowly enough that it does not propagate the way propane or natural gas would. The safety standards that cover them, UL 60335-2-40 and ASHRAE 15, were written with that behavior in mind.
What it means in practice is a set of changes to how equipment is built and installed rather than any change to how you live with it. A new R-454B system in a Pittsfield Township colonial is not a hazard sitting in the basement. The refrigerant is sealed in copper, the charge is small relative to the volume of the house, and the equipment has features specifically designed to handle a leak. For perspective, the natural gas feeding the furnace next to it and the propane cylinder on the grill outside are both far more flammable than anything in the new refrigerant class, and nobody thinks twice about those.
What is physically different on the new equipment
- Refrigerant leak sensors. Indoor coils and air handlers now carry a sensor in the cabinet. If it detects refrigerant, the control board shuts down the compressor and runs the blower to disperse the gas below any concentration that could matter. On a furnace-and-coil setup, the furnace board may need to be A2L-compatible to take that signal, which is one reason a 2025 coil cannot always be dropped onto a 2008 furnace.
- Charge size limits tied to room size. The standards limit how much refrigerant can be in a system relative to the floor area of the smallest room the coil serves. For typical residential charges this is rarely a constraint, but it is a calculation the installer has to do.
- Different service ports and fittings. A2L systems use left-hand-thread or otherwise distinct fittings so R-410A gauges and cylinders cannot be mistakenly connected.
- Labeling. New equipment carries flammability markings, and the line set and indoor coil are tagged so a future technician knows what is in the pipe before opening it.
- Tools. Recovery machines, vacuum pumps and leak detectors must be rated for A2L use. Brazing procedures emphasize a nitrogen purge, which good installers were doing already.
What did not change: your existing R-410A system
This is the part that gets misreported. There is no requirement to replace an R-410A system, no deadline after which it cannot be repaired, and no ban on R-410A refrigerant itself. The production phasedown reduces how much new R-410A is made each year, which will raise its price over time, but reclaimed R-410A will be around for decades. If your 2014 condenser in Canton needs a capacitor or a contactor or a recharge after a leak repair, we fix it the same way we did last year.
Manufacturers were also allowed to sell through inventory of R-410A equipment built before January 1, 2025, with install-by deadlines that ran through 2025 and into early 2026. Those deadlines are now behind us, so a distributor in Wayne or Washtenaw County is no longer able to supply a new R-410A condenser for a residential split system. Some homeowners in Washtenaw County got a good deal on a 2024-built R-410A system during that window, and those systems are perfectly legitimate. They just entered the market as the last of their kind.
What a replacement looks like now
When we quote an AC installation in 2026, we are quoting A2L equipment, and a few things about the job are different from two years ago. We confirm the furnace control board can accept the leak-sensor input or plan for a compatible furnace or add-on board. We calculate the charge against the room size, which in a 1950s Westland ranch with small bedrooms is a step we actually do rather than assume. We use a new line set when the old one is the wrong size, is kinked, or cannot be verified clean, and we pressure-test with nitrogen and pull a deep vacuum before charging, which is not new but is now explicitly expected. The permit and inspection process through the City of Ypsilanti, Ypsilanti Township or Washtenaw County did not change, but inspectors are now looking for the A2L labeling.
If you are replacing an R-22 system from the 1990s or early 2000s, you are jumping two refrigerant generations at once; our R-22 phase-out guide covers the starting point. The efficiency gain is substantial. A 10-SEER unit from 1998 replaced with a 15.2-SEER2 R-454B system uses roughly a third less electricity for the same cooling, which on a DTE bill through a humid August is a real number.
Should you wait, or replace now?
We get this question a lot from people whose R-410A system is 15 years old and limping. The honest answer is that there is no reason to wait for the next refrigerant. R-454B and R-32 are the long-term residential standard for the foreseeable future, the equipment has been through two full cooling seasons in the field, and early reliability has been in line with the R-410A systems it replaced. If anything, waiting means paying the climbing R-410A price for a recharge on a system that is going to need replacement anyway. Our repair or replace framework applies the same way it always has: a compressor or coil failure on a system past year 12 tips the decision toward a new matched system, and a capacitor or fan motor does not.