| 摘要 |
PURPOSE:To reduce liquid back action to a compressor with an inexpensive method and hereby secure reliability of the compressor by providing compressor operation frequency determining means for changing the operation frequency of the compressor upon defrosting operation in response to an output signal from compressor freezer oil temperature detection means. CONSTITUTION:In an air conditioner that performs cold/heating operation by a freezer cycle in which there are successively connected a compressor l, a four-way valve 5, an outdoor heat exchanger 4, pressure reducing means 7. and an indoor heal exchanger 6, there is provided a compressor freezer oil detector 13 for detecting lubricating freezer-oil temperature of the compressor 1. In defrosting operation, there are compared compressor freezer-oil temperature outputted from the compressor freezer-oil temperature detector 13 with a predetermined value, and when the compressor freezer-oil temperature is higher than the predetermined value, operation frequency of the compressor l is increased to improve defrosting capability. When a liquid-back amount is increased and hence the compressor freezer oil temperature is lowered beyond the predetermined value, the operation frequency of the compressor is reduced and hence the liquid-back amount is reduced. The operation is repeated during the defrosting operation.
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