The invention relates to a heating, ventilation and/or air conditioning device for a motor vehicle, comprising at least a first air circulation channel (F1), a second air circulation channel (F2), an air inlet casing (30) mounted upstream of said first and second circulation channels (32, 34) with respect to the direction of air circulation (F1, F2), the casing (30) being traversed by a first air inlet channel (32), opening opposite the first circulation channel, and by a second air inlet channel (34) opening opposite the second circulation channel, the first and second air inlet channels (32, 34) being separated by a first separation partition (36). At the level of the casing, the surface area of the air passage section of the first air inlet channel (32) is different from that of the air passage section of the second air inlet channel (34).
