PURPOSE: To make it easy to regulate the concentration of the solution of an absorbent agent and switch concentration cycle by providing a condenser with a piping which leads a coolant liquid to an evaporator and a piping which has a coolant discharge valve, and providing a low temperature regenerator with a piping which leads a solution to an absorbing device and a piping which has a solution discharge valve.

CONSTITUTION: A condenser 2 is provided with a piping 23 which leads a coolant liquid from the upper section of the coolant pan 18 of the condenser 2 to an evaporator 3 during room cooling operation and a piping 25 which is provided with a discharge valve 24 to discharge the coolant liquid from the lower section of the coolant pan 18 during room heating operation. A low temperature regenerator 16 is provided with a piping 26 which leads solution to an absorber 4 through a heat exchanger 5 from the upper section of the low temperature regenerator during room cooling operation and a piping 28 which is provided with a solution discharge valve 27 to discharge the solution from the lower section of the low temperature regenerator during room cooling operation. With this constitution, when the solution of an absorbent requires a high concentration cycle, the coolant liquid is collected to the coolant pan 18 of the compressor 2, and when the solution of the absorbent requires a low concentration cycle, the solution is colleced to the low temperature regenerator 1b and at the same time the coolant liquid stored in the condenser 2 is discharged to switch the concentration cycles of the absorbent solution and coolant liquid to two stages of high concentration and low concentration.