3.3 Common Refrigerants: Properties, Applications, and Phaseout Status
Key Takeaways
Legacy CFCs R-11 and R-12 had production banned in 1996; R-12 has the highest GWP of any common refrigerant at 10,900
R-22 (HCFC, ODP 0.055) has had no U.S. production or import since January 1, 2020 — existing equipment is serviced with recovered, reclaimed, or previously produced R-22
R-410A (HFC blend, GWP 2,088) and R-134a (HFC, GWP 1,430) are zero-ODP workhorses now being replaced for their GWP under the AIM Act
Lower-GWP replacements include R-32 (GWP 675), R-454B (GWP 466), and R-1234yf (GWP <1) — all A2L mildly flammable
Natural refrigerants R-744 (CO2, GWP 1, very high pressure) and R-717 (ammonia, GWP 0, toxic B2L) are growing in commercial and industrial use
The exam expects you to recognize the major refrigerants by name, know what equipment they serve, and state their regulatory status. This reference walks through them by family, following the same chronological story the industry lived: chlorinated CFCs and HCFCs gave way to zero-ODP HFCs, which are now yielding to lower-GWP A2L blends, HFOs, and natural refrigerants.
Legacy CFCs — Phased Out, Legacy Equipment Only
R-11 (trichlorofluoromethane) is a CFC and the ODP reference standard (1.0). With a boiling point of about 74.9°F, it boils near room temperature, making it a classic low-pressure refrigerant used in legacy centrifugal chillers. Its GWP is 4,750. Production was banned in 1996.
R-12 (dichlorodifluoromethane) is an A1 CFC (ODP 1.0) once dominant in pre-1994 automotive AC and household refrigerators. Its boiling point is about −21.6°F. Its defining exam fact is the highest GWP of any common refrigerant: 10,900. Production was banned in 1996.
HCFC — Still Encountered in the Field
R-22 (chlorodifluoromethane) is the HCFC every technician still meets. It is A1, ODP 0.055, GWP 1,810, with a boiling point of about −41.4°F and roughly 121 psig at 70°F (a high-pressure refrigerant). No R-22 has been produced in or imported into the U.S. since January 1, 2020 — existing systems are serviced with recovered, reclaimed, or previously produced R-22. It served residential and commercial AC, heat pumps, and commercial refrigeration.
R-123 is an HCFC chiller refrigerant, classified B1 (higher toxicity). It boils at about 82.2°F, above room temperature, making it a low-pressure refrigerant like R-11. Its ODP is 0.02 and it is being phased out by 2030.
HFCs — Zero ODP, Now Being Phased Down
R-134a is a single-component HFC (A1, ODP 0, GWP 1,430), a medium-pressure refrigerant (~70 psig at 70°F) used in chillers, pre-R-1234yf automotive AC, and commercial refrigeration.
R-410A is a near-azeotropic HFC blend of R-32 and R-125 (50/50), A1, ODP 0, GWP 2,088. It is a high-pressure refrigerant in EPA's classes (~201 psig at 70°F — roughly 60% higher than R-22, but in the same class) used in residential and commercial AC and heat pumps. Since January 1, 2025, new residential and light commercial AC and heat-pump systems using it may be installed only if all specified components were made or imported before that date, because its GWP exceeds the 700 limit; existing systems may still be serviced.
R-404A is an HFC blend (A1, ODP 0, GWP 3,922 — among the highest of any common HFC). A high-pressure refrigerant for commercial and transport refrigeration, it is a primary phasedown target. R-407C is a zeotropic HFC blend (GWP 1,774) used as an R-22 retrofit; its glide means it must be charged as liquid only.
Lower-GWP Successors — The 2026 Story
R-32 (difluoromethane) is a single-component HFC, A2L (mildly flammable), ODP 0, GWP 675, used in new mini-splits and small AC. R-454B is a zeotropic blend of R-32 and R-1234yf (68.9/31.1), A2L, GWP 466 — the leading R-410A replacement in new equipment, with operating pressures near-identical to R-410A. R-1234yf is an HFO, A2L, GWP <1, the dominant automotive AC refrigerant replacing R-134a.
Natural Refrigerants — Growing Adoption
R-744 (CO2) has GWP 1 and ODP 0 but is a very high-pressure refrigerant requiring specially rated equipment and pressure relief; it is used in commercial refrigeration and heat pumps. R-717 (ammonia) has GWP 0 and ODP 0 but is toxic and mildly flammable (B2L); it dominates large industrial refrigeration. R-290 (propane) is a hydrocarbon with GWP 3, A3 (highly flammable), used in self-contained commercial and household appliances under tight charge limits.
Pressure-Temperature Reference (at 70°F)
| Refrigerant | Pressure at 70°F | Boiling Point | Pressure Class |
|---|---|---|---|
| R-410A | ~201 psig | −60.8°F | High |
| R-404A | ~175 psig | −51.0°F | High |
| R-407C | ~133 psig | −46.4°F | High |
| R-22 | ~121 psig | −41.4°F | High |
| R-134a | ~70 psig | −15.1°F | Medium |
| R-11 | vacuum | 74.9°F | Low |
| R-123 | vacuum | 82.2°F | Low |
Worked Example: A supermarket rack uses R-404A and the owner asks why the contractor recommends replacement instead of a top-off. R-404A has a GWP of 3,922 — among the highest of any common HFC — making it a top AIM Act phasedown target, so future refrigerant will become scarce and costly. Because R-404A is a zeotropic blend, any leaked charge has likely fractionated and must be recovered and recharged as liquid, not topped off. The technician recovers the existing charge, then evaluates a lower-GWP retrofit — showing how phaseout status, blend behavior, and recovery rules intersect on the exam.
Which refrigerant has the highest Global Warming Potential (GWP)?
R-22 (1,810)
R-12 (10,900)
R-410A (2,088)
R-404A (3,922)
What is the current regulatory status of R-22?
Still produced in limited quantities for new equipment
Completely banned — cannot be used in any equipment
No U.S. production or import since January 1, 2020; existing systems may be serviced with recovered, reclaimed, or previously produced R-22
Production ends in 2030
Which of these is the leading lower-GWP replacement for R-410A in new residential/commercial AC equipment?
R-134a (GWP 1,430)
R-454B (GWP 466, A2L)
R-404A (GWP 3,922)
R-123 (GWP 77)
The natural refrigerant R-744 (carbon dioxide) has a GWP of ___, the baseline value for the entire GWP scale.
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