Over a period of time, refrigerator coils frost up catching the humidity from the food and from room air when the door is opened. The refrigerator system defrosts the ice on the coils by turning on a heater. If the heater doesn't turn on or there is a problem with controls or thermostat, unremoved frost (or ice) covers the cooling coils and reduces the refrigerator or freezer and eventually the refrigerator or freezer fails to cool the stored food or other stuff. It is a easy fix if the heater is found defective.
I replaced the heater in a Kenmore side-by-side refrigerator with a model number of 363.9552714.
Heater part number is WR51X442.
Tools needed - Screw Driver, 6mm socket and optionally a multi-meter.
The heater kit looks like below. It contains two heater elements in series and a thermostat. Thermostat clips on to the cooling coil and closes the circuit when the temperature is low. Refrigerator turns on the power to heater when thermostat closes the circuit.
A closer look of it shows the wire harness and a thermostat.
To test the heater assembly you can use a multi-meter. Set the multimeter to read resistance. Connect the two leads of the multimeter to those of the heater wire harness as shown. If the heater is good, you will see a reading
Below is the frosted coil.
1. Remove contents and racks on freezer side of the refrigerator. To remove the rack, pull it up on the right side and then pull.
2. Turn off the power to the refrigerator to avoid getting electrocuted. Remove the panel by releasing the four screws. Two of those screws release by screw driver and the other two release by 6mm socket.
Take a picture of the connections and heater elements placement. This picture comes handy as a reference when you replace the heater with a new one.
Disconnect the heater harness and pull the thermostat away from the coil.
Remove the four screws and pull the harness out
Connect new harness and secure the heating coils with screws.
Install the freezer panel and put back the racks.
Turn on the refrigerator and test the cooling after 24 hours.