Q. The compressor will not stop and is not building up pressure:
Check that the drain plug under the receiver is fully closed.
Q. There is a small hissing noise when the receiver is empty and the compressor starts:
A. This is quite normal, the (ON/OFF) pressure switch is designed to depressurize the pump before starting and will discharge some air as the compressor is building up pressure.
Q. The compressor has stopped and will not restart:
A. The electric motor has a thermal protection and if the compressor has been running for too long, or has been used with an unsuitable extension lead or adaptor, the thermal protection will activate, it will reset itself once the electric motor has cooled down.