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Refrigerant Overcharge — Symptoms, Diagnosis, Recovery to Spec
Likely causes
Abnormally high discharge + subcooling >15°C — condenser partially flooded
Check: Standard diagnosis: high-side >0.3 MPa above normal + subcooling >15°C confirms overcharge. Touch lower condenser; broad cool zone = liquid flooded. Suction line is colder than normal — sign of liquid slugging risk.
What to do: 1) Recover in 200g increments — wait 5 min after each recovery, remeasure. 2) Repeat until target: subcooling 5–10°C + high-side normal ±0.1 MPa. 3) Store recovered refrigerant in recovery cylinder; label (type, recovery date, weight). 4) Document nameplate vs actual charge difference in service report.
Long-term effects — sustained overcharge damages compressor and piping
Check: Abnormal vibration/noise during compressor operation (liquid slugging sign), power consumption +15% over rated, abnormal sweating/frosting on suction line. Long-term: compressor valve damage → reduced discharge efficiency → permanent performance loss.
What to do: 1) Immediately recover to spec to restore proper charge. 2) Diagnose compressor — measure current/vibration/noise vs normal. Abnormal = already damaged → consider replacement. 3) Share overcharge cause with user or prior tech to prevent recurrence. 4) Monitor 1 week post-service for pressure stability.
Cause — accumulation from 'assume undercharge → top off' without leak repair
Check: Check service history — multiple 'top-up' records over 6 months to 1 year strongly suspect unrepaired leak. Pressure starts normal but rises over time pattern.
What to do: 1) Full recovery + recharge to spec (nullifies cumulative top-up). 2) Simultaneously perform leak check — history may suggest leak location. 3) After leak repair, evacuate again and recharge to spec. 4) Educate user — 'top-up is short-term workaround; the real fix is leak repair'.
Overcharge most often comes from accumulated 'top-ups'. Every charge should be: full recovery → charge to spec by weight. Topping off creates the same problem for the next tech.
All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.
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