HFO-1234yf
For HFO-1234yf, ashrae safety class is A2L, verified against its source on 2026-08-11.
- Refrigerant
- HFO-1234yf verified
- ASHRAE safety class
- A2L verified
- Retrofit / new
- retrofit per federalregister.gov
- Listing status / notes
- acceptable, subject to use conditions per federalregister.gov
What the source says
ASHRAE 34-2024 categorizes HFO-1234yf and R-444A as being in the A2L Safety Group and R-453A, R-456A, and R-480A in the A1 Safety Group.
— federalregister.gov, retrieved 2026-08-11
What federalregister.gov says
List HFO-1234yf as acceptable, subject to use conditions, in retrofit light- and medium-duty vehicle (LMDV) motor vehicle air conditioning (MVAC), in new MVACs on buses, and in new MVACs in heavy-duty on-highway (HDOH) vehicles;
— federalregister.gov, retrieved 2026-08-11
Source
- federalregister.govhttps://www.federalregister.gov/documents/2025/11/10/2025-19812/protection-of-stratospheric-ozone-listing-of-substitutes-under-the-significant-new-alternatives