Whirlpool WPW10491891 Refrigerator Defrost Thermostat

The Whirlpool WPW10491891 is a defrost thermostat, which is an essential component in any Whirlpool, Amana, or Maytag refrigerator. The automatic defrost cycle, which keeps frost from accumulating inside the freezer compartment, relies heavily on its bi-metal thermostat. It operates similarly to a temperature switch. The thermostat detects a dip in temperature and activates the defrost heater when ice builds up on the evaporator coils. The accumulation of frost is subsequently melted back into water by the heater, which then turns on and drains away. When the temperature climbs above a certain threshold, the thermostat resets and the cooling cycle restarts. Excessive ice buildup from a defective defrost thermostat can lead to difficulties such as clogged vents. decreased cooling effectiveness, and even damage to the evaporator plates.