Defrost heaters are used for the prevention of ice build up on freezer and evaporator coils. Construction: Stainless steel sheathed element with brass or stainless steel fins for quick heat dissipation.Defrost function is a feature on every air conditioner and is designed to remove the ice build-up on the outdoor unit heat exchanger.Defrost systems are designed to produce just enough heat to melt the ice that has gathered on the evaporator coil. The cycle doesn't last long enough to affect the interior temperature of the cabinet, much less the food held there.Defrost heaters are commonly located beneath a refrigerator's evaporator coils. You will have to remove any objects that are in your way such as the contents of the freezer, freezer shelves, icemaker parts, and the inside rear, back, or bottom panel.