AIR-CONDITIONING MACHINE

PURPOSE:To improve the durability of a compressor as well as the comfortable property of air conditioning and permit to prevent unnecessary operation and stopping of the compressor by a method wherein the heat release value of a heater for assisting room heating is set at the optimum value in accordance with the load of air conditioning. CONSTITUTION:The air-conditioning machine is equipped with an inverter circuit 3, supplying the driving electric power of predetermined frequency and voltage, a control means, controlling the output frequency and voltage of this inverter circuit 3, and the heater 20 for assisting room heating. A control unit 40, connecting the heater to the output terminal of the inverter circuit, switches a four-way valve 11 and detects an indoor temperature by an indoor temperature sensor 41. When the indoor temperature is lower than a set temperature, the inverter circuit 3 is driven and the switch 43 of the heater 20 is put ON. When the inverter circuit 3 is operated, a compressor motor 2M is operated by the AC electric power of predetermined frequency and voltage, which is outputted from the inverter circuit 3, and the compressor 2 is started.