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Liquid Refrigerant Entering Compressor (Flooded Start / Liquid Slugging)

Likely causes

Refrigerant migration — refrigerant migrates into crankcase during shutdown

Check: Verify crankcase heater operation (surface temp ≥ 40°C); listen for abnormal noise/vibration on restart

What to do: Install or replace crankcase heater (mandatory below 12°C ambient); preheat at least 6 hours before start

Expansion valve superheat too low — liquid refrigerant enters suction line (TXV superheat target: 5~8°C)

Check: Check TXV bulb position — mounted at 12 o'clock and insulated; measure superheat on-site (evaporator outlet temp minus suction saturation temp)

What to do: Tighten TXV adjustment screw to achieve 5~8°C superheat; re-seat bulb at 12 o'clock + insulate with ArmaFlex ≥13mm

Oil blockage in evaporator — impedes refrigerant flow, then sudden flooding

Check: Check for hunting (rapid fluctuation) in evaporator outlet superheat; inspect oil return line for blockage

What to do: Install oil trap in evaporator; set oil return cycle; consider installing suction line accumulator

Field tip

Scroll: liquid slugging damages scroll set. Reciprocating: connecting rod breakage. Screw: rotor damage possible. Heavy knocking at startup → stop immediately and diagnose.

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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