Air conditioning system for a motor vehicle

The air conditioning system (1) has an evaporator (2) and a heater (3) installed in an air ducting housing (4). At least one channel (6) is provided in the ducting housing after the evaporator for the draining away of condensation water. The channel is located on the side of the evaporator on a projecting wall (5) between the evaporator and the heater, and extends parallel to the evaporator. The drain channel is trapezoidal or rectangular in form.