Refrigerator compressor running constantly?

A thermistor that reads warmer than actual temperature causes the control board to keep the compressor running continuously to chase a setpoint it can never confirm.

Likely causes · most likely first

Thermistor (Temperature Sensor)

Moderate DIY Part: $15–$40
Condenser Coil

Easy DIY Part: $0–$10

A severely dust-clogged condenser coil traps heat and raises refrigerant head pressure, reducing efficiency and forcing the compressor to run longer.
Evaporator Assembly

Moderate DIY Part: $80–$200

An iced-over evaporator reduces cooling efficiency, causing the thermostat to never see setpoint temperature and the compressor to run non-stop.
Electronic Control Board

Moderate DIY Part: $80–$180

A defective control board may fail to properly read thermistor signals and never issue a compressor cutoff command.
Condenser Fan Motor

Moderate DIY Part: $20–$55

A failed condenser fan motor allows heat to build on the condenser coil, reducing system efficiency and forcing continuous compressor operation.

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