An air conditioner for automotive vehicle use intended to prevent a defrosting operation in an instantaneous foot-defroster mode. The DEF mode in which air mainly from a DEF opening is blown toward the windshield is set by an exclusive front DEF switch. The F/D mode for blowing a substantially equal amount of air to the windshield and the feet of the occupants from the DEF opening and the FOOT opening, respectively, together with the other blow modes (FACE, B/L, FOOT), are sequentially switched for each operation of the blow mode switch in a predetermined sequence. In the case where the F/D mode is selected, the air condition control operation is not performed nor is the blow mode displayed in F/D mode before the lapse of a predetermined length of time (about 1 second). In the case where the blow mode other than F/D mode is desired, therefore, the unrequired control operation in F/D mode is not performed and the instantaneous change is not displayed even though the F/D mode is unavoidably passed-through.