| 摘要 |
A refrigerating air conditioning system is provided with a refrigerant circuit which includes a compressor 3, an indoor heat exchanger 6, a first pressure reducing device 10, an outdoor heat exchanger 11, and a switching device 4 for switching a direction of a refrigerant flow between heating and cooling modes for supplying heat from the indoor heat exchanger 6. In the system, a refrigerant temperature detection sensor 14c of the outdoor heat exchanger 11 and an outdoor air temperature detection sensor 14d are provided for determining a state of a frost formed on the outdoor heat exchanger 11. Two types of defrosting inhibition time values tau1 and tau3 are allowed to be set in accordance with a previous defrosting time tau2 for continuously performing heating operation. A defrosting operation is performed by controlling the defrosting inhibition time value to be long when an amount of the frost formed on the outdoor heat exchanger 11 is determined to be small, and the defrosting inhibition time value to be short when the amount of the frost formed on the outdoor heat exchanger 11 is determined to be large.
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