Check Valve
A plate and spring are provided on the suction side of the rear head. When there is a large difference between the high and low pressures immediately after the compressor has stopped, reverse rotation of the compressor could cause counter flow to the evaporator, as no suction valve is provided. For this reason, a check valve is provided to prevent counter flow. Immediately after the compressor has stopped, the high pressure refrigerant forces the check valve up to close the suction side piping passage and prevent counter flow from the high to low pressure side.