Abstract: An actuator for an air-conditioner for use in a vehicle includes an actuator housing for accommodating a motor, a reduction gear unit and a position-detecting unit. The motor has a shaft extending therefrom with a worm gear fixed to the shaft. The reduction gear unit includes a helical gear that is adapted to engage the worm gear, another gear that supports an output shaft, and a plurality of spur gears positioned between the helical gear and the gear that supports the output shaft. The position-detecting unit includes an output shaft-inserting cylinder which has brushes mounted thereon. The output shaft-inserting cylinder is removably fixed to the output shaft. A printed circuit board having switching patterns thereon that are adapted to engage the brushes and the output shaft-inserting cylinder are mounted at predetermined positions in a position detecting unit housing.