A refrigerator defrost heater is a resistive heating element that melts the ice on refrigerator evaporator coils. It is used because the evaporator coils in the refrigerator tend to collect moisture - which eventually turns into ice. By periodically melting this ice, the coils can continue to efficiently remove heat from the refrigerator. Defrost heaters work in conjunction with defrost timers (or defrost boards) and defrost thermostats. This is so that they don't continue to heat the evaporator coil when not needed. Since they run very hot and are used frequently, they are a common failure point in refrigerators.
How to buy
There are numerous websites out there that sell Defrost Heaters. Pay close attention to the price and shipping charges. Many websites will charge a low price for
Defrost Heaters, but a high price for shipping. Also, try to
from the original equipment manufacturer (OEM), if possible. This will help ensure that they are within the proper specifications for your appliance.
Troubleshooting and Repair Tips
How can you tell when your refrigerator defrost heater is bad? The heaters are resistive elements that get hot when voltage is applied to them. The circuit is usually completed by virtue of a defrost timer (or defrost board), and a defrost thermostat. The defrost heaters commonly fail because the burn out - causing an open circuit. A common symptom is ice build up on the evaporator coils that results in a warm refrigerator due to insufficient air flow. The defrost heater elements can be tested as follows: First unplug the refrigerator. Remove the panel exposing the evaporator coils in the freezer. Melt any ice build up on the coils. Remove the wires on each side of the defrost heaters. Set your multi-meter for ohms. Connect the leads to both sides of the heating elements. Infinite resistance means that the heating elements are bad. They should be replaced with elements that meet specifications based on your model number. Replace the elements and reassemble the evaporator housing. Plug the refrigerator in. If the defrost heaters were the only problem (it is rare for both the heaters and other items go bad at the same time), then the issue with the refrigerator should be solved. Other things to consider: Defrost heaters are part of a complete system that is dedicated to removing frost and ice from the evaporator coils. They often work in unison with a defrost thermostat, timer (or adaptive control), and/or a thermistor. Identifying a bad defrost heater is usually pretty straight forward by checking continuity. However, a defrost element can also be intermittent. This can be due to the small breaks in continuity of the internal connections, the external connections, or the element itself. This is due to the large amount of current that passed through these connections and the tendency for the resistance of the connections to result in heat and ultimately burning and breakage. Intermittent behavior can be associated with such connections as they the distances involved are extremely small. Carefully set your multimeter to continuity or ohms with at least one side of the defrost heater out of circuit. Move the defrost heater around to make sure there is no significant change in reading. If you replace the defrost heater, try to find out the underlying cause. Check the defrost thermostat. If it is stuck in the closed state, the defrost heaters will be on for the entire defrost cycle which is not a good thing. You don't want to replace the heater and have it burn out a week later because ofa a stuck defrost thermostat. Finally, always clean the condnser coils to make sure everything is running as efficiently as possible.
This appliance repair blog applies to Whirlpool, Kenmore, Maytag, GE, General Electric, or Frigidaire defrost heaters.
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Although we offer general repair information, we recommend that a professional is hired to perform any actual repairs.