Quick answer
most new mini-splits sold in the U.S. now use R-454B or R-32 instead of R-410A. The reason is an EPA rule under the AIM Act that caps the global warming potential (GWP) of refrigerants in new residential air conditioners and heat pumps at 700. Existing R-410A systems can still be repaired, and the refrigerant your unit uses is not a reason by itself to pick one model over another: compare SEER2, HSPF2 and cold-climate capacity instead.
On this page
The rule
The American Innovation and Manufacturing (AIM) Act of 2020 directs the EPA to phase down hydrofluorocarbons (HFCs) and lets it restrict their use sector by sector. EPA’s Technology Transitions rule does that. For residential and light commercial air conditioning and heat pumps, including mini-splits, the limit is a GWP of 700, with an installation compliance date of January 1, 2025 for new systems (EPA). R-410A is above that limit, so new systems built from components made on or after that date have to use a lower-GWP refrigerant such as R-454B or R-32.
The exception for older components
New R-410A systems whose specified components were manufactured or imported on or after January 1, 2025 can’t be installed in U.S. residential and light commercial applications (EPA). Systems whose specified components were all manufactured or imported before that date are treated differently: EPA’s reconsideration final rule, published May 26, 2026 and effective July 27, 2026, removed the installation deadline for these systems, where all specified components were domestically manufactured or imported before January 1, 2025 (Federal Register 2026-10387). So you may still see leftover R-410A stock for sale, but new production for U.S. homes has moved to lower-GWP refrigerants.
The three refrigerants side by side
| R-410A | R-454B | R-32 | |
|---|---|---|---|
| What it is | Blend of R-32 and R-125 | Blend of R-32 and R-1234yf | Single compound (difluoromethane) |
| GWP (IPCC AR4, the values EPA’s rule uses) | 2,088 | 466 | 675 |
| Under the 700 GWP limit? | No | Yes | Yes |
| ASHRAE 34 safety class | A1 (non-flammable) | A2L (mildly flammable) | A2L (mildly flammable) |
| Where you’ll see it | Older and leftover stock | Many U.S. brands, including MRCOOL DIY 5th Gen | Many imported and global brands |
GWP compares the warming effect of a refrigerant with the same mass of carbon dioxide over 100 years. EPA lists the GWP of each substitute on its SNAP pages; values above are rounded as commonly published. If a listing gives a different figure, it may be using a newer IPCC report (AR5 or AR6), which produces slightly different numbers.
What “A2L” means for a homeowner
A2L refrigerants are classed as lower-toxicity and mildly flammable under ASHRAE Standard 34: they are hard to ignite and burn slowly, but they are not inert like R-410A. Equipment designed for them is built and certified to UL 60335-2-40, which sets rules such as minimum room size for a given refrigerant charge and, for larger charges, a refrigerant leak sensor that turns the fan on. For you this means:
- Follow the manual’s minimum room area and line-set limits. They depend on the charge, and a long line set adds charge. [Not verified for every model: check your unit’s installation manual for its exact figures.]
- Use only parts and tools the maker approves for that refrigerant. Vacuum pumps, recovery machines and leak detectors used on A2L systems need to be rated for them.
- Keep ignition sources away during service, as the manual describes.
What it means for you
- Buying new: you will most commonly see R-454B or R-32. MRCOOL’s DIY 5th Gen uses R-454B (MRCOOL brochure, checked October 12, 2026).
- Servicing existing R-410A systems: the rule restricts new installations, not repairs of existing ones. R-410A is still produced under the HFC phasedown, but supply shrinks over time, so a major leak on an old system can become more expensive to fix. We don’t publish refrigerant prices because they change quickly.
- Mixing refrigerants: never. A system runs only on the refrigerant it was designed and labelled for. There is no approved “drop-in” swap from R-410A to R-454B or R-32 in an existing mini-split.
- Matching indoor and outdoor units: an R-454B outdoor unit needs indoor heads listed for R-454B. You can’t keep old R-410A heads and replace only the condenser.
- Who can handle it: buying and handling HFC refrigerants is covered by EPA’s Section 608 rules, and per EPA, connecting or disconnecting pre-charged lines on a mini-split requires Section 608 technician certification; see our guide to EPA 608 and DIY mini-splits.
Does the refrigerant change efficiency?
Not in a way you can shop on. Efficiency depends on the whole design: compressor, coils, controls and line set. Compare the AHRI-certified SEER2 and HSPF2 ratings of the exact indoor/outdoor combination (AHRI Directory), and for cold climates look at rated capacity and COP at 5°F. Our SEER2 and HSPF2 explainer and cold-climate guide cover both.
FAQ
Is R-410A banned?
New R-410A systems whose specified components are manufactured or imported on or after January 1, 2025 do not meet the 700 GWP limit for U.S. residential and light commercial installations. Existing systems can still be serviced with R-410A.
Is R-454B better than R-410A?
It has a much lower GWP (466 vs 2,088). Efficiency depends on the equipment design, so compare SEER2 and HSPF2, not the refrigerant.
Is R-32 or R-454B safer?
Both are A2L (mildly flammable) under ASHRAE 34. Install either exactly as the manual says, including room-size limits.
Can I add R-454B to my R-410A mini-split?
No. Use only the refrigerant on the unit’s nameplate.
Sources
- EPA, Technology Transitions HFC restrictions by sector: https://www.epa.gov/hfcs/technology-transitions-hfc-restrictions-sector
- Federal Register 2026-10387 (EPA reconsideration rule): https://www.federalregister.gov/d/2026-10387
- MRCOOL DIY 5th Gen brochure: https://doxrepo.mrcool.com/mc-diy-5-br-en-01.pdf
- AHRI Directory of Certified Product Performance: https://www.ahridirectory.org/