Refrigerant Mixing Prohibited — R-22 / R-410A / R-32 / R-454B Compatibility

Incidents from mixing + compatibility table

Check: **Incidents from mixing**: ① Abnormal pressure rise → compressor damage (R-410A pressure is 1.6× R-22). ② Oil incompatibility → bearing wear (R-22 mineral oil vs R-410A/R-32 POE synthetic). ③ A2L flammability conflict (R-32 + R-410A mix = flammable + non-flammable mixed = unclear rating). ④ System efficiency drop 30–50%. **Compatibility table** (✓ = OK, X = forbidden): R-22 only ✓ / R-410A only ✓ / R-32 only ✓ / R-454B only ✓. **Retrofit possible**: R-22 → R-407C/R-422D (separate procedure, see other case).

What to do: **On suspected mixing**: 1) System OFF + breaker OFF. 2) Recover all refrigerant (no reuse — dispose). 3) Full vacuum, then triple evacuation (remove moisture/residual gas). 4) Replace compressor oil (oxidation/degradation from mixing). 5) New filter-drier mandatory. 6) Recharge with the exact refrigerant on the nameplate by weight. **Don't keep using a mixed system**: 90%+ chance of compressor damage within 5 years. Recovery KRW 50–150k + recharge 50–100k vs new system 2M+ KRW — weigh cost/benefit.