# HFO-1234yf — HVAC refrigerant replacements: retrofit compatibility, safety class, GWP and lubricant

For HFO-1234yf, ashrae safety class is A2L, verified against its source on 2026-08-11.

- **Refrigerant:** HFO-1234yf _(verified: appears in the quote below)_
- **ASHRAE safety class:** A2L _(verified: appears in the quote below)_
- **Retrofit / new:** retrofit _(per federalregister.gov, not stated by the source above)_
- **Listing status / notes:** acceptable, subject to use conditions _(per federalregister.gov, not stated by the source above)_

## 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.

## 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;

Source: https://www.federalregister.gov/documents/2025/11/10/2025-19812/protection-of-stratospheric-ozone-listing-of-substitutes-under-the-significant-new-alternatives

## Source

- https://www.federalregister.gov/documents/2025/11/10/2025-19812/protection-of-stratospheric-ozone-listing-of-substitutes-under-the-significant-new-alternatives

Last verified: 2026-08-11. Review by: 2027-08-11.
Part of [HVAC refrigerant replacements: retrofit compatibility, safety class, GWP and lubricant](https://referencesource.org/hvac-component-refrigerant-compatibility/).