PURPOSE: To prevent the erroneous operation of a temperature sensor, while improving environmental comfortableness and energy saving property by a constitution wherein, when the fan revolution is automatically adjusted corresponding to room temperature, the pseudo setting resistor is connected at specified interval and time to turn the fan forcibly.

CONSTITUTION: The alternate switching circuit 40 alternately switching a pseudo set resistor 35 and two other resistors is connected to the thermostatic circuit 28 in parallel. In this constitution, when the fan revolution is adjusted by the difference between the temperature setting signal of temperature adjusting variable resistor 28 in the central direction unit 21 and the signal of temperature sensor 34, the pseudo setting circuit 35 is connected in place of the room temperature setting circuit resistor 28 at the specified interval and time to turn the fan forcibly regardless of set temperature and measured temperature. Through these procedures, the air around coil starts convection to prevent the sensor 34 from cooling and heating as well as erroneous operation thereof.