A defrost
timer is nothing more than a timed switch that controls
the flow of current to one side of the compressor or defrost
heater.
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Checking your defrost timer
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Manually
place the defrost timer in the defrost cycle and wait approximately
thirty minutes. If the timer motor is working properly and
the thermostat inside your refrigerator is calling for cooling
at the time the defrost timer switches back to the cooling
cycle, the refrigerator compressor should start running.
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A simple way to test your defrost heater without professional
equipment
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This
is a simple test to help you determine if the defrost heater
element is working. This test should not be relied upon
to diagnoses a system.
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Assuming
that your refrigerator has completed a full refrigeration
cycle (Note #1) and assuming the termination thermostat
(Note #2) is working properly, manually place your defrost
timer in the defrost cycle and allow it to advance on its
own for approximately five minutes. With your kitchen lighting
dimmed, manually pull the refrigerator plug from the wall
receptacle. If the defrost heater is working, you should
see a pronounced arc when you remove the plug. Other than
the small defrost timer motor and some small door heaters,
the defrost heater is the only device that would produce
a pronounced arc while your refrigerator is in the defrost
cycle.
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Note
#1:
This is to make sure the evaporator coil has a sufficient
buildup of ice crystals and the defrost termination thermostat
is in the closed position.
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Note
#2:
Defrost termination thermostat (nonadjustable):
The defrost termination thermostat is usually located next
to the evaporator coil and is inaccessible to the average
homeowner. When the coil temperature rises above approximately
60 degrees, the defrost termination thermostat will open
and switch off the defrost heater. When the coil temperature
drops below approximately 15 degrees, the defrost termination
thermostat will close, thus allowing the defrost heater
to engage during the next defrost cycle.
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Disclaimer:
The information contained on these pages should never be
relied upon as a repair guide or be used to make repair
decisions.
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