| 摘要 |
PURPOSE:To prevent a compression ratio of a compressor from being decreased to or lower than its usable limit value, by providing protective means for forcedly making an operating frequency of the compressor equal to or higher than a predetermined frequency when an outside air temperature detected by an outside air temperature sensor meets with a set condition which is beforehand set. CONSTITUTION:A temperature of an outside air sucked by an outdoor heat exchanger 6 is detected by an outside air temperature sensor 13 to be inputted into protective means 14. When an outside air temperature meets with a set condition inputted from condition setting means 15, the protective means 14 compensates an operating frequency calculated by an operating frequency calculating means 9 to forcedly make the same equal to or higher than a predetermined frequency, so that the operating frequency is outputted to an inverter 11. The condition setting means 15 serves to make the operating frequency equal to or higher than 26 Hz at the time of heating operation, for example, when an outside air temperature is equal to or higher than 18 deg.C. Accordingly, a compressor is increased in number of revolution and so its displacement is increased, so that its compression ratio can be prevented from being decreased to or lower than its usable limit value.
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