A DEFROST TIMER is a cycling device, it times the frequency and duration that the defrost heater coils melt the ice that builds up around the evaporator coils. If ice is allowed to build up, air will not be able to freely flow past them - resulting in reduced efficiency and sometimes a drastic warming of the cooling unit.
Most of the time, the defrost timer is in the cooling mode, allowing the compressor to activate when the thermostat signals it to. The remaining part of the cycle (usually less than 30 minutes)the timer is in defrost mode. In this mode, it signals the defrost heaters to melt the ice build up on the coils. This defrost action is limited by the defrost thermostat. If your DETROST TIMER go to bad, one symptom would be if your refrigerator is not cooling. Although
there are many causes of this symptom, A stuck defrost timer can be one
of them. The timer can get stuck in cooling (compressor activated) or
defrost mode (defrost heaters activated) for usually two reasons:
timer motor can fail for one.
- The gears can also become locked up.
matter what the reason is or which mode the defrost timer gets stuck in,
the refrigerator can stop cooling. When the refrigerator is stuck in
defrost mode, the compressor no longer comes on to cool the unit. If the
timer gets stuck in cooling mode, the evaporator coils never get a
chance to defrost, causing ice build-up to the point where there is a
complete blockage of airflow past the coils.
The defrost timer can also
cause the refrigerator to stop cooling due to failure of the internal
switch which activates either the compressor or heater coils. Finally, when doing any
repair on a refrigerator, check the condenser coils for dust buildup and
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