Four way valve is a representative valve which is used for heat pump type air conditioner. This valve functions to selection flow direction of superheated refrigerant discharged from compressor. In heating operation, the valve feeds the refrigerant to indoor heat exchanger. While in cooling and defrosting in heating, the valve feeds to outdoor heat exchanger. For VRV system standard unit, one four-way valve is installed, however, for some units of other series, plural valves may be installed. Moreover, there is two-way valve or three way valve operated with the same mechanism.