A refrigerator uses basic refrigeration principles to extract the heat from air. Refrigerant circulates between an evaporator and a condenser in a closed system that provides a continual cycle of cooling.

The refrigerator box is heavily insulated so that very little heat is absorbed from the outside air and little cold air escapes. Most refrigerator/freezers introduce chilled air into the freezer section; from there the cold air can pass into the refrigerator. Controls regulate how much cold air may pass.

Today, most refrigerators are frost-free. They have automatic defrosting systems so that you don't have to take everything out of your refrigerator to melt built-up ice in the freezer. An automatic defrost system includes a timer, a limit switch, and a heater, which melts away frost.

When refrigerators fail it is unlikely to be caused by the refrigeration system but rather with the unit's electrical controls such as the timer or temperature control.

Ideal temperature
The ideal temperature for a freezer ranges between minus five and plus five degrees F and between 36 and 38 degrees F for the fresh food section.