PURPOSE: To provide a multiroom separation type air conditioning apparatus which is well balanced with economical heat efficiency and performs air-conditioning operation of each room in a stable state by providing a capacity control means to control capacity of a compressor and the opening of a flow control valve by inputting outputs from a temperature sensor, a overheat temperature detecting part, and a detecting part for the number of air-conditioning devices under operation.

CONSTITUTION: A temperature sensor 12 mounted on the delivery side of a compressor 1 enables detection of a gas refrigerant delivered from the compressor. Overheat temperature detecting parts 23 and 24 detect at 13 and 14 a suction temperature being the temperature of a gas refrigerant sucked by the compressor and a vaporizing temperature at which a liquid refrigerant not overheated is vaporized by an indoor heat exchanger. A capacity control means 10 inputs temperature detected by the temperature sensor and controls the temperature of a gas refrigerant delivered from the compressor to a set value by means of a temperature set part 26. From a suction temperature and a vaporizing temperature, the degree of overheat of the whole of a refrigerant flowing in the indoor heat exchanger is calculated by means of a degree of overheat calculating part 25. The opening of a flow control valve 5 to control a flow rate is varied and controlled by an opening control part 28, and an amount of heat exchange effected by an indoor heat exchanger 4 is controlled by a frequency control part 27 to vary and control air-conditioning capacity.