Assembly of an instrument panel in the interior of a motor vehicle

The arrangement has an insulating layer that covers an end wall and a window cross beam (14). The defroster ducts are formed below the instrument panel (10) in vehicle transverse direction, for supplying outflow air supplied to windscreen (12). An outflow opening (24d) is formed in the defroster-wall region forming cantabria portion. A wall portion (24a) is pivotable about an instrument panel-side pivot axis (30), to cover the channel cavity of the defroster channel (28) and to define the force applied downwardly in the direction of windshield.