When an overload protector cracks or gets weak, it loses its ability to transmit power long enough for the compressor to reach its initial speed. As soon as the overload protector warms, it disrupts the power, causing the unit to short-cycle.
Under normal conditions, a motor compressor operates at 125°F (52°C). When the temperature rises to about 225°F, the overload protector opens the circuit to de-energize the compressor motor. When the motor cools to about 160°F, the bimetal in the overload protector flexes and closes the circuit to energize the compressor motor again. In many commercial compressor motors, a solid-state overload protector is placed within the compressor and connected in the circuit. This type of overload protector is referred to as the thermistor type. Hermetic compressor motors that are equipped with internal overload protectors are replaced when the overload protector becomes defective.