| 摘要 |
PROBLEM TO BE SOLVED: To suppress a reduction in capability caused by defrosting operation effectively while the defrosting operation is being carried out completely. SOLUTION: A main defrosting mode in which an air heat exchanger 2 is operated as a condenser is performed while one of a load heat exchanger 4 and a heat taking heat exchanger 3 is operated as an evaporator under a state in which supplying of refrigerant against the other of them is being cut when the air heat exchanger 2 is frosted under its load corresponding mode, or while both the load heat exchanger 4 and the heat taking heat exchanger 3 are being operated as an evaporator. Subsequent to this main defrosting mode, a return transmittance mode in which the load heat exchanger 4 and the air heat exchanger 2 are operated as a condenser in series-connected state under a state in which the load heat exchanger 4 is set at a downstream side while the heat taking heat exchanger 3 is being operated as the evaporator. The operation is returned from the main defrosting mode to the load corresponding mode through the return transmittance mode.
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