PURPOSE: To achieve a smooth switching between cold and warm operation and a stabilization of operation against changes in a pressure difference between equipment as caused at the start by arranging a switching means between a generator and an absorber and a condenser and an evaporator and a control means for the operation of a valve in a refrigerant liquid downflow path and a pump in a refrigerant liquid pumping path.

CONSTITUTION: The passage of a three-way valve V1 or V10 is switched by a cold/warm changeover switch to change a temperature level of a fluid flowing through a heat exchanger 11 or 14. A controller CO is connected by an electric line to a value VR, a pump PR for a refrigerant liquid and a pump RA for an absorbent liquid to control them. In the cooling operation with a witch SW closed to the cold position, the discharge pressure and the discharge of the pump PA for the absorbent liquid is controlled by the controller CO to increase or decrease according to variations in the difference between the pressures detected by sensors SH and SL. On the other hand, the valve VR for adjusting the downflow of the refrigerant liquid is controlled to increase or decrease. In the heating operation, receiving a closing signal to the hot position of the switch SW, the controller CO controls the discharge pressures and the discharge of the pumps PA and PR according to variations in the pressures detected by the sensors SH and SL.