The U.S. Environmental Protection Agency (EPA) is taking direct final action to revise one of the use conditions required for use of hydrofluoroolefin (HFO)-1234yf (2,3,3,3-tetrafluoroprop-1-ene), a substitute for ozone-depleting substances (ODSs) in the motor vehicle air conditioning end-use within the refrigeration and air conditioning sector, to be acceptable subject to use conditions under EPA's Significant New Alternatives Policy (SNAP) program. The revised use condition incorporates by reference a revised standard from SAE International.