PURPOSE: To provide the same volume of wind regard less of the frequency of an electric source, without using a rotation sensor, by using such a control means that can control the electric power supply so that the electricity supplied for the motor will be reduced when the detected frequency of the electric source is 60Hz than that when the frequency was 50Hz.

CONSTITUTION: A microcomputer 30 functions both as a control means and a frequency detecting device, to which signals from a clock pulse generation circuit 33, an electric power switch 34, a temperature sensor 35, an power sensor 36 of a PTC heater 28, a switch input part 37, a door switch 38 and a detection process circuit 39 are inputted. The microcomputer 30 outputs drive control signals to a drive device 41 to drive a motor 11, the PTC heater 28, and a buzzer 40 based on the inputted signals and control programs. The electric power to be supplied to the motor 11 is controlled to be less when the detected frequency of the electric source is 60Hz than that when the frequency was 50Hz. In this condition, the electric power to be supplied to the motor 11 is controlled to be increased if the detected electricity of the PTC heater 28 is less than the prescribed value.