The Significant New Alternatives Policy (SNAP) program has approved a number of acceptable alternative refrigerants for motor vehicle air conditioners (MVACs), subject to use conditions. It is important for both consumers and technicians to be aware of these alternative refrigerants, their properties, and proper servicing procedures. Learn more about the transition to new MVAC refrigerants.

Most MVACs operate using chlorofluorocarbonchlorofluorocarbonA compound consisting of chlorine, fluorine, and carbon. CFCs are very stable in the troposphere. They move to the stratosphere and are broken down by strong ultraviolet (UV) light, where they release chlorine atoms that then deplete the ozone layer. CFCs are commonly used as refrigerants, solvents, and foam blowing agents. The most common CFCs are CFC-11, CFC-12, CFC-113, CFC-114, and CFC-115. The ozone depletion potential (ODP) for each CFC is, respectively, 1, 1, 0.8, 1, and 0.6. A table of all ozone-depleting substances (http://www.epa.gov/ozone/science/ods/index.html) shows their ODPs, global warming potentials (GWPs), and CAS numbers. CFCs are numbered according to a standard scheme (http://www.epa.gov/ozone/geninfo/numbers.html). (CFC)-12, hydrofluorocarbonhydrofluorocarbonA compound consisting of hydrogen, fluorine, and carbon. The HFCs are a class of replacements for CFCs. Because they do not contain chlorine or bromine, they do not deplete the ozone layer. All HFCs have an ozone depletion potential of 0. Some HFCs have high GWPs. HFCs are numbered according to a standard scheme (http://www.epa.gov/ozone/geninfo/numbers.html). (HFC)-134a, hydrofluoroolefin (HFO)-1234yf, or carbon dioxide (R-744). HFC-152a may be used in the future.

The Society of Automotive Engineers (SAE) International has developed SAE Ground Vehicle Standards for use of these alternatives. The standards, also known as SAE J Standards, are available at http://standards.sae.org. Exit Look for additional safety information on refrigerant containers, vehicle manufacturers’ manuals, and lubricants.

Refrigerants in Use

CFC-12 (Relevant SAE Standard: J639)

CFC-12 was used in MVACs until the 1990s. It is an ozone-depleting substance and a greenhouse gas with a high global warming potentialglobal warming potentialA number that refers to the amount of global warming caused by a substance. The GWP is the ratio of the warming caused by a substance to the warming caused by a similar mass of carbon dioxide. Thus, the GWP of CO2 is defined to be 1.0 . CFC-12 has a GWP of 8,500, while CFC-11 has a GWP of 5,000. Various HCFCs and HFCs have GWPs ranging from 93 to 12,100. Water, a substitute in numerous end-uses, has a GWP of 0. A table of all ozone-depleting substances (http://www.epa.gov/ozone/science/ods/index.html) shows their ODPs, GWPs, and CAS numbers, and another table shows the GWPs for many non-ozone-depleting substances (http://www.epa.gov/ozone/geninfo/gwps.html).. Automobile manufacturers began to transition to non-ozone-depleting refrigerants in 1992-model-year vehicles. Since 1995, all new vehicles sold in the United States use a non-ozone-depleting refrigerant.

HFC-134a (Relevant SAE Standard: J639)

HFC-134a is the most common MVAC refrigerant used since the 1990s. Although HFC-134a does not deplete the ozone layer, it is a potent greenhouse gas with a high global warming potential.

HFO-1234yf (Relevant SAE Standards: J639, J2844, J1739)

HFO-1234yf is a climate-friendly refrigerant. It is mildly flammable, but can be used safely. SNAP listed HFO-1234yf as acceptable subject to use conditions on March 29, 2011 (76 FR 17488) (PDF)(34 pp, 455 K, About PDF).

R-744 (Relevant SAE Standards: J639)

R-744 is a climate-friendly, high-pressure refrigerant. R-744 systems operate at five to 10 times higher pressure than other MVAC systems. SNAP listed R-744 as acceptable subject to use conditions for new vehicles only; the final rule was published on June 6, 2012 (77 FR 33315) (PDF) (17 pp, 346 K, About PDF).

R-744 is exempt from the refrigerant venting prohibition. However, it is not exempt from the Section 609 requirement to properly use certified refrigerant handling equipment. Only certified technicians can work on R-744 MVAC systems.

Refrigerants for Future Use

HFC-152a (Relevant SAE Standards: J639, J2773)

HFC-152a is a climate-friendly refrigerant that may be pursued in the future. HFC-152a is flammable, but can be used safely. SNAP listed HFC-152a as acceptable subject to use conditions for new vehicles only; the final rule was published on June 12, 2008 (73 FR 33304) (PDF)(8 pp, 377 K, About PDF). Only certified technicians can work on HFC-152a MVAC systems.

Certification Requirements

Technicians certified before 2015 were not trained to service MVAC systems using HFO-1234yf, R-744, or HFC-152a. At this time, EPA does not require technicians to recertify to work on these systems.