An air conditioner having a refrigerant circuit that maintains a high cooling efficiency and a sufficient amount of oil returned to a compressor even if the flow rate of refrigerant is decreased due to a low cooling load is provided. The refrigerant circuit includes a condenser, an expansion valve, an evaporator and a variable displacement compressor. The expansion valve is normal-charge type. A control valve adjusts the pressure in a crank chamber based on the value of a current from a controller and on a pressure difference between two pressure monitoring points, which are located in the refrigerant circuit. Accordingly, the compressor displacement and the flow rate of refrigerant in the circuit are controlled.