Abstract: A motor vehicle heating, ventilating and/or air conditioning installation has a control panel comprising a light box which consists of a housing comprising a housing member with an open side closed by a front wall of the control panel, and a light source within the housing. The front wall is of translucent material made opaque on its front face except in lighting zones which define illuminated indicia. Some of the lighting zones have a first thickness, while others are of different thicknesses, so that the luminance of the lighting zones at the front face of the front wall is modified locally. In this way, imperfections in the light box arising from differences in luminance in the illuminated indicia can be compensated for.

Abstract: A flap (11) for controlling the flow of air in a duct, in particular in a heater or air conditioner installation for the cabin of a motor vehicle, comprises an assembly of two half-flaps (12) applied against each other and each having projecting hollow stiffener ribs (13) disposed substantially opposite to one another, to constitute a hollow box structure. A sealing ring (17) is moulded over touching peripheral rims (16) of the half-flaps. For given stiffness, this structure may four or five times lighter than a conventional sheet metal flap, thereby reducing the force needed to actuate the flap.