Abstract: An air conditioner is provided for a motor vehicle which controls the division of the blow-out air by individually adjusting the blow-out air temperature of the center vent, right side vent and left side vent over a broad temperature range. The blow-out air temperature is controlled from the upper and lower and right and left blow-out parts by the passengers of the motor vehicle to place the cabin of the motor vehicle into a comfortable temperature range. The conditioned air within the conditioned air passages is responsive to load conditions both inside and outside of the passenger compartment to individually adjust the temperature of the conditioned air. A first and second auxiliary duct which introduces cool air from the upstream side of the air mix door and warm air from the downstream side of the heater unit into the conditioned air flows through the right side vent duct, and left side vent duct, respectively.