AIR CONDITIONER

PROBLEM TO BE SOLVED: To prevent abnormal overheating of a power transistor module. SOLUTION: As shown in Fig. 1, this air conditioner is provided with a refrigerating cycle formed by connecting a compressor 12 of which rotational frequency is variable in multiple stages by an invertor device, an outdoor unit 9 comprising a four-way valve, an outdoor heat exchanger, an outdoor fan 51 for distributing the air to the outdoor heat exchanger, an outdoor control device, an outside air temperature sensor 50 or the like, and an indoor unit 1 comprising an indoor control device or the like, by refrigerant pipes, a refrigerant heating device 16 for heating a bypass circuit formed in parallel with the outdoor heat exchanger, is mounted in the outdoor unit, and the air is guided to a cooling fin for cooling the power transistor module by the air distributed by the outdoor fan 51 for cooling the power transistor module, an electric current sensor is mounted for detecting an electric current value flowing in the power transistor module, and an outdoor fan operating means is mounted for controlling the operation of the outdoor fan 51 in accordance with the electric current value of the electric current sensor and the outside air temperature in heating operation. COPYRIGHT: (C)2006,JPO&NCIPI