A vehicle air conditioner casing has defrost, face, and front seat floor vents variably communicating with a mixing chamber. Air passageways in the casing include an evaporator and heater core. A rear seat console vent communicates with a warm air passageway including the heater core and a cool air passageway through a console side cool air bypass passageway on the casing bottom surface, under the heater core. A front seat temperature adjusting door adjusts variably opens cool air passageway outlets and the warm air passageway with respect to the mixing chamber. A rear seat main temperature adjusting door variably opens warm air passageway inlets and the console side cool air bypass passageway. A rear seat auxiliary temperature variably adjusts the openings of warm air passageway outlets and the console cool air bypass passageway with respect to the rear seat console vent.