The part(s) or condition(s) listed below for the symptom Freezer defrost drain frozen are ordered from most likely to least likely to occur. Check or test each item, starting with the items at the top of the page.
A frozen freezer defrost drain can be caused by the freezer temperature being too cold. If the temperature is significantly below 0° Fahrenheit, you should use a multimeter to test the temperature control thermostat for appropriate changes in resistance as the thermostat cools down or heats up. If the resistance doesn't change or there's no resistance at all, the thermostat is defective and will need to be replaced.
The drain strap may have fallen off or deteriorated. Some freezers have a small copper or aluminum strap that attaches to the defrost heater and extends into the defrost drain. When the defrost heater turns on, heat is conducted through the drain strap to melt any ice that may have accumulated in the defrost drain. If the drain strap is defective, it will not be able to melt the ice, causing the defrost drain to frost over.
A frozen freezer defrost drain can be caused by the freezer temperature being too cold. If the temperature is significantly below 0° Fahrenheit, you should use a multimeter to test the thermistor for appropriate changes in resistance as the sensor cools down or heats up. If the resistance doesn't change or there's no resistance at all, the thermistor is defective and will need to be replaced.
Defrost the drain and make sure the drain is clear. Using a turkey baster with warm water will help clear the ice and any clogs quicker. The water should flow freely into the tray by the compressor. If the drain is clogged the drain strap will not keep the water from freezing.
A frozen freezer defrost drain can be caused by the freezer temperature being too cold. If the temperature is significantly below 0° Fahrenheit and the freezer's thermistor shows appropriate resistance changes when tested with a multimeter, it's possible the control board is faulty and sending continuous voltage to the compressor. You can inspect the board for signs of burning or a shorted component and replace if necessary.
A frozen freezer defrost drain can be caused by the freezer temperature being too cold. If the temperature is significantly below 0° Fahrenheit and the freezer's thermistor shows appropriate resistance changes when tested with a multimeter, it's possible the user control and display board is faulty and unable to regulate the cooling circuit.
A frozen freezer defrost drain can be caused by the freezer temperature being too cold. If the temperature is significantly below 0° Fahrenheit and the freezer's thermistor shows appropriate resistance changes when tested with a multimeter, it's possible the main control board is faulty and sending continuous voltage to the compressor. You can inspect the board for signs of burning or a shorted component and replace if necessary.
A frozen freezer defrost drain can be caused by the freezer temperature being too cold. If the temperature is significantly below 0° Fahrenheit, you should use a multimeter to test the temperature sensor for appropriate changes in resistance as the sensor cools down or heats up. If the resistance doesn't change or there's no resistance at all, the temperature sensor is defective and will need to be replaced.