A control unit for an air conditioning system for a motor vehicle calculates a target blowing air temperature based on a temperature of a passenger's clothing detected by a no contact temperature sensor. An air conditioning operation is performed based on the calculated target blowing air temperature. In particular, when calculating the target temperature in the summer or in the winter season, a change of the detected temperature of the passenger's clothing is used, so that the change of detected temperature is reflected in the target temperature with a time delay.