According to a conventional air conditioner, when a refrigerating cycle is stopped for a long period of time and a compressor is maintained at a low temperature, a liquid refrigerant accumulates in a compressor suction pipe-line, liquid compression occurs when the air conditioner is activated, and thus a shaft torque becomes excessive. This results in breakage of the compressor.
To provide a compressor driving device for an air conditioner that enables efficient heating from inside of a compressor when the compressor itself is at a low temperature, there has been known a compressor driving device for an air conditioner that applies a fixed alternating-current voltage, which cannot be followed by a movable part of the compressor and has a frequency higher than that of the normal operation, to the compressor at a regular time interval while the operation of the compressor is stopped, and continuously applies a fixed alternating-current voltage to the compressor when a current detecting unit detects a current value higher than a predetermined set value at that time (see, for example, Patent Literature 1).