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If your R-22 system has a leak, you have three routes: repair and recharge with R-22, retrofit to an approved alternative, or replace the system. This page is about the middle one, which is the least understood.
The approved alternatives
| Refrigerant | Also sold as | GWP | Notes |
|---|---|---|---|
| R-407C | Suva 407C, Genetron 407C | 1,774 | The most common R-22 retrofit. |
| R-438A | MO99, Freon MO99 | 2,265 | Marketed as a lower-effort R-22 retrofit because its hydrocarbon additives help return mineral oil, which can avoid a full oil change in some systems. |
| R-422B | NU-22B | 2,526 | Another mineral-oil-tolerant R-22 retrofit. |
| R-417A | MO59, Isceon 59 | 2,346 | An early mineral-oil-compatible R-22 retrofit. |
What a retrofit actually involves
It is a procedure, not a swap. Properly done it means recovering the remaining R-22, usually changing from mineral oil to POE, sometimes changing the metering device, evacuating, weighing in the new charge as a liquid, and labeling the system so the next technician knows what is inside.
Some blends — R-438A and R-422B in particular — include small hydrocarbon additives specifically to help mineral oil keep circulating, which can avoid a full oil change in some systems. That is the main reason a shop picks one over another.
What you give up
Be clear-eyed about this: a retrofit generally delivers somewhat less capacity and efficiency than the system had on R-22 when it was new. It is a way to keep working equipment running, not an upgrade. You are also putting money into a system that is, by definition, at least fifteen years old.
When a retrofit makes sense
It usually does when the system is otherwise healthy, the leak is cheap to fix, and you are looking to buy a few more seasons rather than commit to a replacement now.
It usually does not when the leak is in the evaporator coil or compressor, when the system is already near the end of its service life, or when a large R-22 charge plus a component repair lands close to replacement cost. At that point you are spending real money on old equipment and getting reduced performance for it.
Run the repair-or-replace numbers · More on R-22 availability and cost
Related: R-22 · Can you mix refrigerants? · AC repair vs replace
Frequently asked questions
What can replace R-22 in my existing system?
Approved retrofit refrigerants include R-407C, R-438A (MO99), R-422B (NU-22B), and R-417A (MO59). Each requires a proper retrofit procedure rather than simply adding the new refrigerant, and the system must be labeled afterward.
Is retrofitting cheaper than replacing?
Upfront, usually yes. But it delivers somewhat less capacity and efficiency than the original R-22 performance, and it puts money into equipment that is at least fifteen years old. It buys seasons rather than solving the problem.
Can I just add a replacement refrigerant to my R-22 system?
No. A retrofit requires recovering the existing charge, usually changing the oil, and weighing in the new charge as a liquid. Adding a different refrigerant on top of R-22 creates a mixture with unpredictable properties.
Sources & verification
✓ Verified against a manufacturer, regulator, or standards source
- GWP values computed from the component exchange values in Appendix A to 40 CFR Part 84, the AIM Act regulated-substance list, rather than copied from secondary sources — epa.gov
- EPA, “Homeowners and Consumers: Frequently Asked Questions” (HCFC phaseout) — epa.gov
Last reviewed 2026-08-31. How we verify what we publish →
