R-Pro › Field cases › Components
Oil Separator Heater Open Circuit — Liquid Slugging at Startup
Likely causes
Heater resistance wire open circuit — premature failure from repeated high-temperature exposure (service life 3–5 years)
Check: Measure heater resistance with multimeter — OL (infinite) confirms open circuit; normal heater 50–200 Ω (varies by capacity); also verify 220 V supply with terminals disconnected
What to do: Shut off oil return line and replace heater (external heater band type → replace band only, no separator disassembly needed) → verify thermostat set to 20–40°C
Refrigerant dissolves into oil during prolonged low-temperature storage — liquid slugging at startup
Check: Before startup, check for oil foaming or crankcase abnormal noise; verify heater non-operation history
What to do: Ambient below 10°C: minimum 4 hours pre-heat; below 0°C: minimum 8 hours; start after crankcase heater warm-up → if liquid slugging occurs, stop immediately → replace oil if heavily diluted before restarting
Always verify heater operation before winter startup — resistance check with multimeter takes only 30 seconds; a failed heater leading to compressor damage means repair costs 100x higher
All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.
Open R-Pro →Related cases
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