Before testing the defrost thermostat, unplug
the refrigerator to avoid an electrical shock hazard.
Some defrost systems use a thermostat (a bi-metal
switch) to prevent the defrost heater from overheating. The switch
is normally closed. During a defrost cycle, the defrost heater
causes the metal alloy in the switch to warm and as it does it
curls back and breaks the circuit. As the metal cools, it makes
a circuit again and the defrost heater starts heating again (as
long as the defrost timer is in the defrost cycle). A defective
thermostat can prevent the defrost heater from coming on or allow
it to overheat which could result in heat damage or fire.
The defrost thermostat is located near the defrost
heater and is wired in series. It is usually located at the back
of a side by side freezer or under the floor of a top freezer.
It will be necessary to remove obstructions such as the contents
of the freezer, freezer shelves, icemaker and the inside rear
or bottom panel of the freezer.
Before testing the defrost thermostat, unplug
the refrigerator to avoid an electrical shock hazard.
