| 摘要 |
PURPOSE:To raise defrosting efficiency without giving unpleasant feeling to persons who live in a room by providing a valve in a bypass circuit and opening the valve at the time of starting defrosting operation of an outdoor heat exchanger to make the blast amount of an indoor fan lower than during the room heating operation and changing the blast amount of the indoor fan during defrosting operation. CONSTITUTION:When starting defrosting operation, the pressure on a high pressure side much drops by opening a valve 17 with a sudden drop in the room heating capability, but since the speed of an indoor fan 18 is lowered than during the room heating operation, it is possible to make small the temperature drop of the air blown out into the room after heat exchange with a heat exchanger 13 on the indoor side, so that persons who live in the room will not have unpleasant feeling. Further, as the defrosting proceeds, the pressure on the high pressure side becomes higher gradually and the room heating capability becomes larger, but if the temperature signal from an indoor temperature detection element 21 rises to a set value, then the rotational speed of the indoor fan 18 is lowered by a control circuit 22, and the defrosting capability of the outdoor heat exchanger 15 is raised by suppressing the increase in room heating capability, and it becomes, therefore, possible to improve the defrosting efficiency.
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