To prevent an operation of needlessly-large displacement of a variable displacement compressor in a refrigerant-deficient condition in a refrigerating cycle.
A pressure switch 60 is disposed at an outlet side of an evaporator 4. The pressure switch 60 senses a suction pressure Ps, and outputs a signal indicating that the suction pressure Ps is lower than a set pressure to a control portion 6, when the suction pressure Ps becomes lower than the set pressure. The control portion 6 cuts off power supply to a control valve 5, and transfers a compressor 1 to a minimum displacement operation state, when it receives the signal, and determines that the suction pressure Ps becomes lower than the set pressure. That is, a function of the compressor 1 is temporarily stopped, on the condition that the refrigerating cycle is in the refrigerant-deficient condition, and the suction pressure Ps is lowered.
Yusuke Murata
Tomoyuki Miki
Takuya Matsuo