PURPOSE: To improve a comfortable feeling during a sleeping hour by a method wherein set speeds showing a relation a first set speed > a second set speed, are set as rotating speeds of a control vane and stored, an air direction control vane starts to rotate at the first set speed during a cooling operation and when a sleeping control is started, the air direction control vane is rotated at the second set speed.

CONSTITUTION: When a cooling operation is started at a time to, an indoor fan motor is operated at a set number of revolutions. An air direction control vane 6 is rotated at a first set speed 4.42°/sec within a range from its horizontal state to an angle of 30°C. Since a suction temperature is higher than a set temperature, a compressor is operated. At a time t1, when the suction temperature reaches the set temperature, a compressor stops its operation. However, the indoor fan motor continues its operation at the set number of revolutions and the air direction control vane also continues its operation. At a time t2, when the suction temperature reaches the set temperature +1.5°C, the compressor starts its operation again. At a time t3, when a sleeping control is carried out, the set temperature is shifted to a higher degree by 1°C, the indoor fan motor is changed over to feed a fine air and further the air direction control vane is changed to a second set speed of 2.21°/sec and then the indoor fan motor is operated. Since a relative of the first set speed > the second speed is attained, a periodic varying sound when the air direction control vane is rotated under a rotating of the fan is reduced.