When the refrigerator is running ( cooling mode ) the defrost timer contacts
prevents any power from getting to the defrost heater. When the defrost timer
turns off the power to the compressor and fan motor(s) the power is then
redirected to the defrost system. The defrost timer
motor
Defrost thermostat:
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 closed circuit again. 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, behind the freezer back wall of a top freezer
or under the floor. 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. At room temperature the defrost thermostat is an open
circuit ( no continuity ) and when cooled down the defrost thermostat closes the
circuit ( has full continuity ) to allow the defrost heater to come
on.
Defrost timers:
The defrost timer is sometimes found behind the front grill
of the refrigerator. It may also be found behind a cover plate inside the
refrigerator or freezer, in the temperature control console, or behind the
refrigerator near the compressor.
The timer is usually held in place with one or more screws.
Remove the screws and gently pull the timer out far enough to disconnect the
wiring connector.
Locate the timer switch and turn it
clockwise until you hear it click.
One click and the refrigerator shuts off = defrost mode, second click the
compressor and fans come back on = run/cooling mode.
*Some defrost timers are a constant or continuous run timer, which
means when ever the refrigerator is plugged in the defrost timer is powered up
and running. Some defrost timers are an accumulative run timer, which means when
the refrigerator is off the defrost timer is off and not running, when the
refrigerator is running the defrost timer is running. This is also sometimes
called a demand defrost. The power for the defrost timer goes through the cold
control first on an accumulative defrost system. The timers are often the same
but will be wired differently to get the different operations.
Defrost heater:
Test the heating element for
continuity using a multimeter. Set the multimeter to
the ohms setting X1. Place a probe on each terminal. The multimeter should
display a reading somewhere between zero and infinity. Because of the number of
different elements we cannot tell what your reading should be, but we can be
certain of what it shouldn't be. If the reading is zero or infinity the heating
element is definitely bad and should be replaced. Proper power ( careful!! ) to
the heating element ( 110-120 volts AC ) and the defrost heater does not come on
= bad defrost heater.
Some newer refrigerators have been
using an electronic board instead of an mechanical defrost timer. The adaptive defrost control does the same job as the
defrost timer ( shuts off the refrigerator cooling items and redirects the power
to the defrost heater for the defrosting cycle, then redirects the power to the
compressor and fans to come back on when the defrost cycle is over ). This
adaptive defrost system is a bit different when testing, normally speaking if
the defrost heater and defrost thermostat ohm ok, we replace the adaptive
defrost board.
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Hello Friend, I am happy to assist you! I understand you are seeking the location of the defrost timer on your Frigidaire refrigerator; however, it appears above-listed model number is invalid. You may normally find the serial tag (which lists your model number) inside the cabinet, on the left/right side wall. With this information I can provide the correct location to you. Thank you! - Z
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