A head-up display in a motor vehicle has an image combiner movable between an active position, in which it is situated in the field of view of a driver of the vehicle, and an inactive position, in which it is situated close to a surface of or within an instrument panel. The position of the image combiner is controlled depending on signals from vehicle devices that indicate a likelihood or probability of a fogging condition of the windshield. The fogging condition may be indicated by a driver actuation of a windshield defogging/heating system.