To suppress heat transfer from high-temperature coolant via a valve casing of a four-way selector valve.

An air conditioner 10 includes a refrigerating cycle formed by connecting a compressor 12, the four-way selector valve 30, an indoor heat exchanger 18, a decompression means 16, and an outdoor heat exchanger 14 through coolant piping, and a control device 50 for performing air-conditioning operation by switching the four-way selector valve. A high-pressure side conduit 22 of the four-way switching valve 30 is arranged to face to an indoor-side conduit 26 in an approximately straight line manner. The indoor-side conduit 26, a low-pressure side conduit 24, and an outdoor-side conduit 28 are welded to a valve seat 34. The four-way selector valve 30 uses the valve seat 34 formed of brass material added with 1-4% manganese to reduce a heat transfer amount from high-temperature coolant to low-temperature coolant via the valve seat, and uses the compressor 12 in which an increased amount of heating capacity generated by reduction of the heat transfer amount of the valve seat 34 is larger than an increased amount of compressor input generated by reduction of the heat transfer amount.

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