Freestanding Freezer: What should I do when my freezer's high-temperature alarm sounds?

The compressor start relay starts the compressor and keeps it running until the compressor cycles off. Replace the start relay if it's broken and the compressor doesn't run. In some situations, a wiring failure could be causing the problem, and repairing the start relay wiring will fix the problem.

The electronic control board-also called the main control board or the power control board (PCB)-manages the compressor and the defrost cycle. The control board activates the compressor to keep the freezer cold and runs the fans. The electronic control board monitors temperature sensors to control freezer temperature and the defrost cycle. Replace the electronic control board if it's not working properly.

The control panel houses the selection buttons and the display for the freezer. The control panel communicates with the electronic control board through a wire cable. Check the wire cable connections before replacing the control panel. Replace the control panel when keys are stuck or the display doesn't work.

The freezer defrost sensor-also known as the defrost bi-metal or defrost termination thermostat-is next to the evaporator. It trips when the evaporator temperature gets too high, to protect the evaporator from overheating. When it trips, the defrost bi-metal shuts off the defrost heater. A defective defrost bi-metal prevents the defrost heater from working, causing frost to build up on the evaporator, causing a warmer freezer interior. Replace the defrost sensor if it prevents the defrost heater from working.

The thermistor is a temperature sensor inside the freezer. The electronic control board uses the reading from the thermistor to cycle the compressor on and off to maintain freezer temperature. Replace the thermistor if it's not sensing freezer temperature accurately.

The evaporator fan mounts on the evaporator assembly. It moves air across the evaporator fins and through the cabinet for cooling. The freezer won't cool properly when the evaporator fan breaks. If the evaporator fan doesn't run when activated, replace it.

Dust-covered freezer coils prevent the freezer from running efficiently and cooling properly. Unplug the freezer and clean the condenser coils using a coil brush. Vacuum up the dust. Clean the grill below the freezer door to allow proper air flow to the condenser.

The defrost timer controls the intervals between defrost cycles and limits the length of the cycle. During the defrost session, the timer activates the defrost heating element and prevents the compressor from running, so frost melts from the evaporator fins. Replace the defrost timer if it doesn't control the defrost heater and compressor properly.

The condenser fan is in the machine compartment of the freezer next to the compressor. It moves air across the condenser coils to help cool the hot refrigerant coming out of the compressor. Replace the condenser fan if it fails to run when activated.

The compressor is a pump that an electric motor rotates. The compressor is the problem if the motor won't start when the start relay actives it, or if the motor runs but the pump doesn't compress the refrigerant. Have a service technician replace the compressor, because this repair requires access to the sealed refrigerant system.

Routine maintenance keeps your freezer working efficiently. Clean the bottom front grill and the condenser coils regularly to help the freezer cool better and use less energy. Adjust the freezer door if it's not sealing properly. Lubricate the door seal with a light coat of petroleum jelly occasionally to prevent air leaks into the freezer.