The Defrost Heater is an OEM replacement part for Frigidaire refrigerators. It is an electric heating element located within the back wall and along the evaporator coil compartment. The heater defrost works to melt any accumulated frost or ice during refrigeration defrost cycles.  Causes of a bad defrost heater include failure of the heating coil or wiring over time due to regular use. Moisture exposure can also degrade insulation and connections. Symptoms of a bad defrost heater include:  Ice buildup inside the refrigerator that does not melt    Inability to maintain proper cooling temperatures Frost accumulating externally on refrigerator coils Unusual smells emanating from within the appliance  This OEM Frigidaire replacement defrost heater restores automatic defrost capabilities. Compatible with some Electrolux, Roper, and Kenmore models as well, regular replacements prevent defrost issues.242094802 (AP5628678) replaces 2309880, 242094801, PS3653489.