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 and icemaker.
Before testing the defrost heater, unplug the refrigerator to avoid an electrical shock hazard.
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 -never force it. If you decide to remove it, you do so at your own risk - it is prone to breaking. Warm it first with a warm, wet bath towel.
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.