Patent ID: 7937960

Claim:
A humidity controller comprising: a refrigerant circuit for performing a refrigeration cycle by circulating a refrigerant, a variable capacity compressor, first and second adsorbent heat exchangers each supporting an adsorbent thereon and a switching mechanism for reversing the direction of a refrigerant circulation flow being connected to the refrigerant circuit, the switching mechanism reversing the direction of the refrigerant circulation flow such that an operation in which one of the first and second adsorbent heat exchangers serves as an evaporator and the other serves as a condenser and an operation in which the one of the first and second adsorbent heat exchangers serves as a condenser and the other serves as an evaporator are alternately carried out and air humidified by the adsorbent heat exchanger serving as the condenser or air dehumidified by the adsorbent heat exchanger serving as the evaporator being supplied to the inside of a room, wherein the switching mechanism is a four-way switching valve which includes a valving element, and reverses the direction of the refrigerant circulation flow by sliding the valving element, the four-way switching valve reverses the direction of the refrigerant circulation flow by sliding the valving element at predetermined time intervals while the compressor is operated, the humidity controller further includes: a differential pressure detector for detecting a difference between high pressure and low pressure in the refrigeration cycle of the refrigerant circuit, and a controller for controlling the capacity of the compressor, the controller reduces the capacity of the compressor when a detected value of the differential pressure detector exceeds a reduction threshold, and the reduction threshold is set to a value at which normal sliding of the valving element of the four-way switching valve is ensured.