According to the present invention, the hardness of a resin material forming an attachment portion (33) of an actuator case (31) is set higher than the hardness of a resin material forming an air conditioning case (10). In the attachment portion (33), an insertion hole for a screw (A) and a projection (33d) are formed. By threading the screw (A) into a boss (18) of the air conditioning case (10), the projection (33d) is wedged into the boss (18).
