Some major parts of a freezer's wiring system are the compressor, overload protector, condensing unit and evaporator unit. Other common components include the door switches, running capacitor and temperature control thermostat. The parts present and their locations vary based on freezer model.
A freezer may fail to cool if there is an issue with one of several possible components of the wiring system. The problem may originate from the condenser coils, condenser fan motor, evaporator fan motor, evaporator coils or compressor. It may also stem from the temperature control thermostat. Dirty condenser coils are a common culprit when a freezer is not operating optimally, and they should be cleaned every approximately six months to keep the unit cooling at full capacity. The freezer may also not work properly if the condenser fan motor is burned out or if it is not spinning because there is something stuck in its blades.
It is also important that the evaporator unit of the freezer's wiring system be properly maintained to keep the unit running smoothly. A malfunctioning defrost system can cause the evaporator coils to frost over, which prevents air from traveling efficiently through the freezer. The evaporator fan motor may stop circulating air throughout the freezer if it is damaged or if the door switch is not properly activated.