How To Repair A Freezer That Will Not Stop Running
- Rated as REALLY EASY
- 40 repair stories
- 6 step by step videos
Temperature Control or Thermostat
If your freezer doesn’t shut off even though the desired internal temperature has been reached, you may have a problem with the temperature control thermostat. The rotary dial thermostat or temperature control uses a capillary tube and bulb sensor that attaches to the inside liner of the freezer to monitor the temperature, and also has a set of internal electrical contacts that supply power to the compressor circuit. As the temperature at the sensor drops, a pressure change occurs at the control and the switch contacts will open and shut off the compressor. If the contacts weld or stick closed, or if the sensor bulb is damaged, the compressor will continue to run regardless of the temperature. Inspect the sensor bulb to ensure that it is properly positioned before replacing the control.
Defrost Timer
If your freezer is a frost free model and continues to run but doesn’t get cold enough, then you may have a problem with the defrost timer. These models use a defrost heater to melt any frost that accumulates on the evaporator coil. The defrost timer is part of this circuit and should cycle the heater on at regular intervals to maintain a frost free evaporator. If the defrost timer fails, the heater may not get energized and the evaporator will become blocked with frost or ice. This will cause the compressor to run almost continuously to try and maintain the set temperature. You can manually advance the defrost timer to start the defrost cycle and if the evaporator defrosts normally, then you will need to replace the timer.
Defrost Thermostat
If your freezer is a frost free model and continues to run but doesn’t get cold enough, then the defrost thermostat may be defective. These models use a defrost heater to melt any frost that accumulates on the evaporator coil. The defrost thermostat is part of this circuit and is used to terminate the defrost cycle when the heater has melted the frost from the evaporator. The defrost thermostat should have continuity when it is at freezing temperatures and should change to open circuit when the temperature rises above approximately 50 degrees Fahrenheit. If the thermostat does not have continuity then the heater will not get energized and the evaporator will become blocked with frost or ice allowing the freezer temperature to rise. The temperature control will sense this increase and cause the compressor to run almost continuously to try and lower the temperature.
User Control or Electronic Display Board
If your freezer doesn’t shut off even though the desired internal temperature has been reached, and your model has an electronic display, then you may have a problem with the user control display board. On some models this electronic control is used to display, monitor, and adjust the internal temperature of the freezer, as well as to control the operation of the compressor, evaporator fan motor, and defrost heater circuits. If the control has failed, it may cause the compressor and evaporator fan motor circuits to remain on continuously. You should also check the thermistor temperature sensor for a defect before you condemn the control.
Defrost Heater
If your freezer is a frost free model that continues to run but doesn’t get cold enough, then the defrost heater may be defective. These models use a defrost heater to melt the frost that accumulates on the evaporator coil. A defrost timer cycles the heater on at regular intervals to maintain a frost free evaporator. If the heater fails, the frost will continue to accumulate on the evaporator until it becomes blocked and no air can circulate through it. This will cause the compressor to run almost continuously to try and satisfy the thermostat control. You can test the defrost heater for continuity with a multi-meter and it typically should show less than 30 ohms.
Door or Lid Gasket
If your freezer doesn’t seem to ever shut off and the desired internal temperature seems normal or is slowly increasing, then you should inspect the door or lid gasket. A damaged or defective gasket can allow warmer room air to enter into the freezer and cause the thermostat to keep the compressor on almost continually. On frost free models, a leaky gasket will also create more frost on the evaporator and restrict the air flow, again causing the compressor to run almost continually. Inspect the gasket to ensure that it is making a tight seal. Look for areas where there is a frost build up where the gasket contacts the cabinet. If it is damaged or has deteriorated, it should be replaced. To prolong the life of the gasket, keep it clean and wipe up any spills as they occur.
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