How Defrost Works In Refrigerators/Freezers

Refrigerators and freezers are designed to keep food and beverages fresh by creating a cool environment that’s below the freezing point of water. Over time, however, a layer of ice will form around the unit’s evaporator coil, restricting the cool air from passing into the unit. The ice acts as an insulator, making the refrigerator work twice as hard to try and stay cool.

Defrosting solves the problem of ice build-up on the evaporator by melting the frost. When the atmosphere surrounding the frost-covered evaporated rises above 32 degrees Fahrenheit, the frost will begin to melt. Some of the early model refrigerators required manually defrosting by disconnecting power to the unit for a given period of time.

Refrigerators and freezers with auto-defrost usually have a temperature control mechanism that tells the unit when to stop cooling. There’s still power running to the unit, but when the internal temperate reaches the specified setting, it will stop blowing cool air into the main compartment until the evaporator has defrosted.