Interesting Facts About R-22

• Phosgene Gas Hazard: When R-22 is exposed to high heat (open flame, brazing torch, or electrical arc), it can decompose into phosgene gas (COCl₂) — a highly toxic choking agent historically used in chemical warfare. This is why proper refrigerant recovery and never venting R-22 (or any HCFC) is critically important.
• Formicary (Ant-Nest) Corrosion: R-22 systems are notorious for a unique form of copper tubing corrosion called formicary corrosion. Moisture + air + certain organic acids (often from lubricant breakdown or contaminants) create tiny, branching pits inside the copper that look like ant nests under magnification. These leaks are extremely difficult to locate and were a common failure mode in R-22 equipment.
• Ozone Depleter: R-22 is a hydrochlorofluorocarbon (HCFC-22) with an Ozone Depletion Potential (ODP) of 0.05. It was one of the last widely used refrigerants to be phased out under the Montreal Protocol.
• Production Ban: Virgin R-22 production and import was banned in the United States after January 1, 2020. Only reclaimed or recycled R-22 can now be used to service existing equipment.
• Excellent Thermodynamic Properties: Despite its environmental drawbacks, R-22 was beloved by technicians because it had outstanding heat transfer, high volumetric capacity, and worked well in a wide range of applications (residential AC, heat pumps, and commercial refrigeration).
• Not a Drop-In Replacement: You cannot simply put R-407C, R-410A, or R-454B into an R-22 system without major changes (TXV/expansion device, oil type, and often the compressor itself). Many "retrofit" blends were developed specifically because true drop-ins don't really exist for R-22.
• Still Very Common: Even in 2026, there are still hundreds of thousands of R-22 systems operating in North America, especially in older homes and light commercial buildings. Many will be replaced rather than repaired as reclaimed R-22 becomes more expensive and harder to source.