In frost-free refrigerators and freezers, a fan is installed over the evaporator to move air through the evaporator and circulate it in the freezer and the fresh-food compartments. If this fan fails to operate, there will not be enough air velocity for an effective heat exchange to prevent a frost buildup on the evaporator coil.
Consequently, frost will build up on the coil. The temperature in the freezer compartment will rise from – 1 0 ° F to 0°F or higher. As a result, the temperature in the fresh-food compartment will rise to room temperature. The same thing happens in air conditioners. If the evaporator blower fails, air will no longer be circulated through the cold evaporator fins, causing an accumulation of ice on the evaporator plate, and a sudden temperature rise in the air-conditioned area.