The principle is the same as in the regular refrigerator with the exception that they come with heavier insulation and a different cold-control range. Normal operating temperatures in freezers range between -14°F and +7°F (see fig. 11).
In freezers with double fans, one draws air from the inside of the cabinet to be circulated over the evaporator while the other one moves the chilled air from the evaporator to the cabinet. Larger commercial units may have three or more fans. They all move air in the same pattern. Depending on the model of freezer, the evaporator coil could be located in the walls, in the back, or even in one or more of the shelves.