To improve energy efficiency, and to extend a service life of an internal combustion engine-driven heat pump type air conditioner.

In the air conditioner, compressors 11 and 12 driven by an internal combustion engine 19 via clutches 19a and 19b are used as variable displacement type compressors with variable displacement. It is composed such that operations of the internal combustion engine, the clutches, and the compressors are controlled such that a controller 40 operates the internal combustion engine in a low engine speed high torque state with favorable energy efficiency, and fluctuation of the required load is coped with by selecting a compressor to be connected to the internal combustion engine and varying the displacement of each compressor within a range wherein a required load with respect to each compressor is small, and the required load is coped with by changing an engine speed of the internal combustion engine with the displacement of each compressor set at maximum within a range wherein the required load is large.

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