PURPOSE: To shorten a time required for defrosting the surface of an outdoor heat exchanger by a method wherein a large amount of liquid refrigerant of high temperature and high pressure accumulated within an indoor heat exchanger before starting a defrosting operation is flowed into the outdoor heat exchanger in concurrent with a starting of the defrosting operation.
CONSTITUTION: Before starting operation of defrosting operation, i.e., before a predetermined time from a time in which a solenoid valve 8 is opened, liquid refrigerant of high temperature and high pressure is accumulated within an indoor heat exchanger 3. The solenoid valve 8 is opened when the liquid refrigerant of high temperature and high pressure is sufficiently accumulated within the indoor heat exchanger 3 after elapsing a predetermined time and then a compressor 1 is stopped in its operation. Then, the liquid refrigerant of high temperature and high pressure accumulated within the indoor heat exchanger 3 flows into an outdoor heat exchanger 4 through a four- way valve, a discharging pipe 9, a hot gas bypassing circuit 6 and a solenoid valve 8 so as to melt frost 7 adhered to the surface of the outdoor heat exchanger 4. The compressor 1 is driven when this state elapses for a predetermined time, i.e., movement of the liquid refrigerant within the indoor heat exchanger 3 into the outdoor heat exchanger 4 is completed, and then the operation is transferred to a normal defrosting operation.
FUJIKI HIRONARI
ITO NOBORU
