PURPOSE: To sufficiently perform defrosting and demisting of a front glass without causing the necessity for using a temperature sensor, by providing a means capable of automatically selecting a blower speed and a mode to an air conditioning device for an automobile.

CONSTITUTION: An air conditioning device for an automobile comprises a blower unit 1, cooling unit 4 and a heater unit 6, and an air mixing damper 9 is provided to the upstream side of a heater core 7, while a vent damper 10 opening and closing a front blower port 11 and the first driving motor 10a are provided. While a heat damper 12 opening and closing a foot blow port 14 and the second driving motor 12a driving the damper 12 are provided, and an outside air temperature sensor 18, blower speed setter device 21 and a mode setter device 20 are equipped. An electronic control unit 15 receives signals from the sensor 18, speed setter device 21, mode setter device 20 and a water temperature detector sensor 16, and calculates the signals to control a blower motor 2 and the driving motors 10a, 12a.