| 摘要 |
PURPOSE: To reduce noise generated when a four way valve is changed over by stopping a compressor once when changing over from heating operation to defrosting operation and balancing the high pressure and low pressure of a heat pump cycle and then changing over the four way valve and restarting the compressor. CONSTITUTION: Refrigerants discharged from a compressor 2 are returned to the compressor 2 by way of a four way valve 3, an indoor heat exchanger 6, a throttling mechanism 5, an outdoor heat exchanger 4 and the four way valve 3, thereby driving a return heating operation. When changed over from the return heating operation to defrosting operation, the operation of the compressor 2 is halted once, thereby producing an equilibrium between the high pressure and the lower pressure in a heat pump cycle. At that time, a controller 20 changes over the four way valve 3 and halts the operation of an indoor fan 8 simultaneously. Then, the compressor 2 is started once again and an outdoor fan 7 is halted, thereby starting defrosting operation. This construction makes it possible to reduce a strange sound generated when the four way valve 3 is changed over. |
