This cold start valve, also referred to as an unloader valve, is supplied by the original manufacturer for use in electric air compressors. It has a length of 0.63 inches, a 1/8-inch male pipe thread, and a hexagonal head for increased stability and security. It allows the compressor to easily start in cold conditions by releasing air pre...Read moressure from the compressor head or the discharge line which reduces the amount of power needed for the motor to start. Once the compressor starts and the pressure in the tank increases, the valve closes and allows pressure to build. If the valve is faulty, the compressor motor will struggle to start, overheat, or trip the circuit breaker. Disconnect the compressor from the power source and open the drain valve to depressurize the tank. Disconnect the pressure switch line from the valve and unscrew the valve using a wrench. Thread the new valve into place and be careful not to overtighten it. Reattach the pressure switch line and close the drain valve to complete the repair.