Refrigerator thermostats work by measuring the amount of warm air present within the unit and cycling it through a cooling mechanism to achieve the desired temperature. The warmth threshold can be set through a dial within the refrigerator.
It is a common misconception that refrigerators maintain a cold temperature by cycling cold air into the unit. Refrigerators don’t actually place new air into the unit, but use the thermostat to monitor temperature and cool the warm air that builds up over time.
Proper use of a refrigerator thermostat begins by setting it at the appropriate temperature. In most cases, a dial is found within the main interior of the unit, usually at the top center. Older models featured actual degrees on the dial, with newer models switching to a numerical ranking system that correlates to an approximate temperature. In order to understand what temperature each number represents, owners can refer to the refrigerator's instruction manual.
Once the thermostat detects the designated amount of warm air, it activates the internal compressor that pumps that warm air out of the storage section of the unit. The air is transferred to a series of coils that connect to a supply of coolant. As the air travels through this coiled piping, it drops in temperature and is fed back into the main body of the unit.