What Is a Refrigerator Thermostat?

Usually located on the inside of a refrigerator, a refrigerator thermostat controls the refrigerator cooling system which can be adjusted using knobs.
A stainless steel refrigerator.
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  • Written By: Dakota Davis
  • Edited By: C. Wilborn
  • Last Modified Date: 05 September 2014
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A refrigerator thermostat is the controlling component of the refrigerator cooling system. This system includes a compressor, a condenser, a metering device, and an evaporator. It works by removing heat from the refrigerator, as opposed to cooling the air inside.

Refrigerator thermostats are usually located inside the refrigerator and have a knob that allows users to adjust them. Once a user sets the desired temperature, the thermostat maintains that temperature by sensing internal fluctuations and prompting the compressor to turn on or off in response to those changes. When the refrigerator is appropriately adjusted to the designated temperature, the thermostat stops the flow of electricity to the compressor, stopping it from cooling the appliance.

The compressor is the engine of the cooling system. About the size of a football, it includes a pump and motor in a sealed compartment where the refrigerator cooling liquid, called refrigerant, travels. When the refrigerator thermostat detects too much heat, the compressor turns on and begins transforming refrigerant from a low-pressure gaseous state into a high-pressure gas.

The refrigerant gas moves from the compressor to the condenser, where it becomes a liquid that gives off heat. The liquid refrigerant is then forced into a capillary tube, which controls the pressure and flow. When the liquid refrigerant reaches the evaporator, it loses pressure and changes back into a gaseous state. This transformation from liquid to gas absorbs the heat in refrigerator, resulting in a cooling effect.


The refrigerator thermostat is different from the defrost thermostat, which works with a refrigerator’s automatic defrost feature. Most modern refrigerators defrost automatically, meaning that frost accumulated inside the refrigerator melts automatically. This occurs because the defrost timer shuts off the refrigerator and turns on the defrost heater, which is located near the refrigerator’s cooling coils. As the heater gets hot, any ice or frost accumulating on the cooling coils melts. The defrost thermostat is placed near the cooling coils and prompting the defrost heater to turn off when the heat near the coils has reached a specific temperature.

An external refrigerator thermostat may be used in the process of beer making or fermenting cheese. These thermostats include a temperature control dial and a probe that is placed inside the refrigerator. The refrigerator is then plugged into the external thermostat, which overrides the internal controls.


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Post 1

My thermostat has markings from 1 to 9 and I am just left to guess which end of the dial is colder. I will assume that 1 is cold and 9 is warm.

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