I have a Kenmore model
HI. There are two causes here, in this situation. The most common will be a faulty defrost timer, or adaptive defrost control board. The defrost mechanism will vary form unit to unit. Most newer units will be equipped with an defrost control board. This will be located in the control housing, just above the heat shield, in the upper right had side. Older models will have a standard defrost timer mechanism. If this device fails, the evaporator heater Assembly will not receive the command to defrost the coil, on time. The easiest way to isolate the cause, will be to test the heater element. If the element is functional, the defrost timer/board, will be the culprit.
Defrost heater assembly test procedure:
The defrost heater 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, ice-maker and the inside rear or bottom panel of the freezer, to access.
The panel may be held in place by retainer clips or screws. Remove the screws or depress the retainer clips with a small screwdriver. On some older top freezers it is necessary to remove the plastic molding to access the freezer floor. Removal of that molding can be tricky, so try not to force it, if possible. If you decide to remove it, you do so at your own risk. it will break, if forced. Warm it first with a warm towel, or hair dryer, set to low heat.
There are three primary types of defrost heater elements; exposed metal rod, metal rod covered with aluminum tape or a wire coil inside a glass tube. All three elements are tested in the same way.
The heater is connected by two wires. The wires are connected with slip on connectors. Firmly pull the connectors off of the terminals (do not pull on the wire). You may need to use a pair of needle-nose pliers to remove the connectors. Inspect the connectors and the terminals for corrosion. If the connectors are corroded they should be replaced.
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 faulty, and should be replaced.
NOTE::----(If indeed the heater and defrost board are functioning as designed, the culprit will then be the actual defrost thermostat. This may or may not be attached to the heater assembly. In some cases, the entire heater Assembly will need to be replaced along with the thermostat.)
Kenmore 56539 /...
on May 03, 2011