Air distribution unit for a heating, ventilation and/or air conditioning system of a vehicle

The unit has three butterfly valves (13a-13c) to control passage of air through air registers (41a, 41b) of air distribution conduits (42a, 42b) by rotation of the valves around a unique axle (15). The unique axle carries the butterfly valves such that the butterfly valves and the axle form a single piece. The air registers are disposed along different planes (46a, 46b). An independent claim is also included for an installation of heating, ventilation and/or air conditioning of a cab interior of a vehicle.