How does air compressor unloader valve work?

An air compressor unloader valve is designed to release air from the compressor's pump when the compressor is not running, preventing pressure build-up in the system. When the compressor reaches its cut-off pressure and shuts off, the unloader valve opens, allowing the stored air in the pump and discharge line to escape. This action reduces the load on the motor during the next startup, making it easier for the compressor to restart. Once the compressor is activated again, the unloader valve closes, allowing the system to pressurize.