A heating and air-conditioning system for a motor vehicle having a conditioning housing in which at least one heat exchanger is integrated and which has a plurality of air outlet openings for guiding air to front interior zones of the motor vehicle is known. According to the invention, the conditioning housing has a connecting section which is provided with at least one air outlet opening and is intended for connecting to an optionally attachable rear temperature-control unit which, when not utilized can be tightly, in a leak-proof manner, closed by a removable covering part.