What it is

For years R-22 was THE residential AC refrigerant. It's an HCFC that got phased out of new equipment and new production for ozone reasons, and R-410A became the standard replacement on new systems. You'll still service plenty of old R-22 equipment, so you need to know both and — critically — know why they are not interchangeable.

The headline differences: R-410A runs much higher pressures, uses a different oil, and demands equipment rated for it. Treat them as two different worlds that happen to do the same job.

How it works

R-410A and R-22 have different pressure-temperature relationships. At the same temperature, R-410A sits at a substantially higher pressure than R-22. That's not a defect — the equipment is engineered around it — but it means an R-22 system isn't built to contain R-410A pressures, and your R-22 gauges' temperature scale is useless on R-410A.

They also use different oils. R-22 systems traditionally run mineral oil. R-410A systems run POE (polyolester) synthetic oil, because mineral oil won't circulate and return properly with R-410A. POE is hygroscopic — it grabs moisture out of the air aggressively — which changes how you handle the system (short open times, good evacuation, fresh driers).

In the field

  • Always confirm which refrigerant you're on before connecting gauges or charging. Check the data tag. Select the correct refrigerant on a digital manifold, or use the matching P-T chart for analog. Pick wrong and every superheat/subcooling number is garbage.
  • Use R-410A-rated gauges, hoses, and recovery gear on R-410A. The higher pressures need the higher rating.
  • Charge as liquid (R-410A is a near-azeotropic blend with very low glide, but charging as liquid is still the rule).
  • Don't mix them and don't "convert" casually. Dropping R-410A into an R-22 system is unsafe (pressure) and wrong (oil). Genuine R-22 replacements/retrofits use specific drop-in or near-drop-in refrigerants with their own procedures and oil considerations — and even those require following the refrigerant maker's retrofit instructions.

Normal values & targets

Representative saturation points showing the pressure gap (chart editions vary slightly):

| Saturation temp | R-22 (approx) | R-410A (approx) | |---|---|---| | 40°F | ~69 psig | ~118 psig | | 50°F | ~84 psig | ~142 psig | | 110°F | ~226 psig | ~365 psig | | 120°F | ~260 psig | ~418 psig |

So at a given condensing temperature, R-410A head pressure runs well above R-22 — roughly 50–60% higher in the ballpark. Suction pressures are higher too. Targets for superheat and subcooling are the same general ranges for both (superheat ~10–20°F at the compressor; subcooling ~8–12°F on a TXV), because those are about the cycle, not the fluid.

Common faults & what they mean

  • Pressures don't match the refrigerant you selected: confirm what's actually in the system. Someone may have topped an R-22 system with the wrong refrigerant, or you've got the wrong refrigerant selected on your gauges.
  • Oil not returning / compressor issues after a refrigerant change: wrong oil for the refrigerant. R-410A needs POE; mineral oil won't return with it.
  • Moisture/acid problems on an R-410A system: POE absorbed moisture during a long open repair. Keep open times short and pull a deep vacuum; replace the liquid-line drier.

Tech tips & gotchas

  • R-22 is phased out, not banned to service. New production and import of virgin R-22 ended, so it's scarce and expensive; you service existing R-22 systems with recovered/reclaimed R-22. That cost is a real factor in repair-vs-replace conversations with customers.
  • POE is a moisture sponge. Leaving an R-410A system open to atmosphere lets the oil pull in moisture fast. Cap things, work efficiently, evacuate deep (~500 microns), and change the drier.
  • Higher pressure means higher stakes. Be deliberate about rated equipment and about not trapping liquid in a hose or recovery cylinder where it can over-pressurize as it warms.
  • Don't assume the gauge's printed temp scale. An older analog set scaled for R-22 will read the wrong temperature on R-410A. Use the right chart or a digital tool set to the right refrigerant.
  • A2L successors are coming. New equipment is moving to lower-GWP A2L refrigerants (like R-454B and R-32). They're mildly flammable and have their own handling rules — different again from both R-22 and R-410A.

Safety / code notes

  • R-410A's higher pressure requires correctly rated service equipment and care to avoid trapping liquid that can over-pressurize.
  • Recover per EPA 608; venting either refrigerant is a violation.
  • Never mix refrigerants in a system; retrofits must follow the refrigerant manufacturer's documented procedure and oil requirements.