The Defrost Thermostat is an OEM replacement part for Frigidaire upright freezers. It is a temperature-sensing device that monitors coil temperatures, triggering the automatic defrost cycle to safely melt frost buildup obstructing airflow. Located near refrigerator coils, the defrost thermostat optimizes energy-efficient defrosting. Causes often relate to regular exposure to fluctuating interior freezer temperatures over extended periods. Impacts compromising calibration can also force early replacement. Symptoms involve: Excessive ice accumulation hinders air circulation and cooling power The inability of the unit to maintain a frost-free interior environment Higher utility costs from the refrigerator constantly fight accumulation This Frigidaire OEM replacement part fits upright models by Electrolux, Gibson, and some Kenmore models.5303918568 (AP5177213) replaces 1865449, AH3493212, EA3493212, PS3493212.