PURPOSE: To avoid an unnatural air blow temperature of an air conditioner, which controls introduced air by an air mix door, at the time or restarting the car, by stopping the action of the air mix door when car speed is slowed down.

CONSTITUTION: The CPU20 of the air conditioner performs air conditioning in accordance with a set temperature Ts memorized by an RAM22, room temperature Ti and car speed Sr. When air-conditioner switch 15 is ON, intake door set at OPEN AIR INTAKE and a blower fan motor 28 is stopped, the control by open air will be performed as the car speed signal Sp is provided. When car speed is slowed down beyond a set value, the air mix door becomes fixed at the present position with both negative and atmospheric pressure solednoids 26, 28 made OFF. Upon restarting the car, the air conditioner is restarted introducing the open air, the same air blow temperature will be maintained as before car stoppage, accordingly.