| 摘要 |
PROBLEM TO BE SOLVED: To prevent the suction side of a compressor from having negative pressure in the latter half of a refrigerant recovery operation even when a heating operation is resumed after the completion of the heating operation and ensure the reliability of the compressor by switching a four-way valve to a heating side after the four-way valve is switched to a cooling side for a prescribed time, closing a two-way valve, operating the compressor and performing the refrigerant recovery operation. SOLUTION: When a heating operation is started, a four-way valve 2 is turned on to be switched to a cooling side. With the lapse of, for example, 10 seconds, the four-way valve 2 is turned off to be switched to a heating side, and a two-way valve 7 is closed so that a refrigerant recovery operation for operating a compressor 1 is performed. When the heating operation is resumed again without much time after the completion of the heating operation, the four-way valve 2 is switched to the cooling side, an outdoor side cooling heat exchanger 6 communicates with the discharge side of the compressor 1 to supply refrigerant in the compressor 1 to the outdoor side cooling heat exchanger 6. When the four-way valve 2 is returned to the heating side to move to the refrigerant recovery operation, the discharge side pressure of the compressor 1 rises and the suction side pressure of the compressor 1 and the pressure of the outdoor side cooling heat exchanger 6 decrease. |
