Refrigerator defrost assembly parts and working procedure?

Most refrigerator problems begin with a failed defroster.
This can lead to sticky smelly ice, a roaring freezer fan and a loss of cold in the refrigerator compartment.

The freezer remains quite cold though, but frost continually builds up.
Manually unplugging the refrigerator will defrost the refrigerator in time, but that will eat up precious hours as your food slowly spoils.

Your defrost circuit consists of a defrost timer:

Defrost heater:

And a Defrost Thermostat:

The weakest link here is the defrost thermostat.
All refrigerators that come equipped with a defrost function use all 3 of these parts.

The second weakest link is the defrost timer since it has an electric motor inside it's case which wears out in time.

Defrost heaters are pretty similar to the heating element on a stove and rarely need replacement.

Every defrost thermostat has a temperature range stamped on the body of the part and should be replaced with the exact same temperature range replacement part. To troubleshoot this part you simply short the 2 wires together which lead to the thermostat to bypass it, rotate your defrost timer until you hear a click and wait for the defrost heater to begin melting the frost. The defrost timer has a tiny hole in the middle with gear teeth protruding outwards. This gear will only rotate one way so you cant make a mistake while rotating to the defrost cycle.

To troubleshoot the defrost heater make sure the thermostat is shorted as mentioned above and that the defrost timer is in the defrost mode.
Now, using either a digital or analog multimeter connect to both leads of the heater and your reading should be 100 to 120 volts AC. If the voltage is there but your heater is cold, you need a new heater.
If the voltage is absent and you get no reading then your timer is defective and will need to be replaced.

Rarely is there more than one failed part in a defrost circuit, and these minor parts are fairly inexpensive.


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