Air flow distribution device for a ventilation, heating and/or air conditioning installation of a vehicle

The air flow distributor consists of a housing (3), made at least partly in the shape of a hollow cylinder, with ports (30, 31) linked to first and second ducts, and a rotary shutter (2) to control the flow between the ducts and a third duct. The shutter has a tripod support (1) with branches (10, 11, 12) centred on its axis of rotation and mounted on a base partition (32), which has an aperture leading to the third duct, and additional supports (21) connected to the inside of the shutter. The axis of the shutter lies parallel to that of the housing but is offset from it to permit the first and second ports to be closed and sealed.