Engine-operated or electrically-operated air conditioner and control method for the same

Disclosed herein are an engine-operated or electrically-operated air conditioner and a control method for the same. The air conditioner is configured so that a compressor (50) thereof is driven by selectively using a driving force transmitted from an electric motor (60) or a driving force transmitted from an engine (70) according to an operational frequency of the compressor, thereby reducing fuel costs as well as ensuring high operational efficiency of the compressor and good cooling/heating performance of the air conditioner, as a result of integrating advantages of electrically-operated and engine-operated compressors.