STRUCTURE OF VENTILATION DUCT FOR VEHICLE AIR CONDITIONING SYSTEM

PURPOSE: A structure of ventilation duct for vehicle air conditioning system is provided, in which an adjustment valve for concentrating the air blown from the blower onto the defrost duct is arranged in the ventilation duct, to thereby effectively remove the frost formed at the side door glass during rain or winter time. CONSTITUTION: An air conditioning system includes a defrost duct(6) and a ventilation duct(7) which are arranged within an instrument panel so as to guide the air blown from a blower to a side defrost grille(11b) and a side ventilation grille(12b), respectively. Disposed between the defrost duct and the ventilation duct is a communication passage(9) for communicating two ducts. An adjustment valve(18) is arranged within the ventilation duct so as to selectively guide the air blown from the blower to the side defrost grille or the side ventilation grill. The adjustment valve includes a first valve(21) and a second valve(22) coupled to an outer shaft and an inner shaft of the adjustment valve, respectively, and which open/shut off the ventilation duct and the communication passage.