the direction of the pivot axis and is separated from the lateral regions 16 by walls 20 at the end of the walls 20 which is on the pivot axis side these are connected by means of a bridge 21 the latter being curved slightly according to the middle region 17 this bridge 21 serves on the one hand as a kind of spoiler with an air guide function and on the other hand for increasing the stability of the louver 6 on that side 22 of the louver 6 which lies opposite the side 18 the regions 16 and 17 terminate at different heights as is evident particularly from fig1 to improve the opening behavior the outer regions 16 are of beveled design that is to say in particular they do not run parallel with respect to the pivot axis the middle region 17 terminates parallel to the pivot axis again an outwardly extending edge 23 being provided which also extends beyond the outside of the outer regions 16 and the end faces 15 as far as the tenons 14 and therefore as far as the edge 19 the functioning of the louver 6 is explained in more detail below with reference to fig3 to 10 fig3 and 4 show the 100 warm position that is to say the louver 6 with all the regions 16 and 17 closes the path for the cold air coming directly from the evaporator 3 in this case the louver 6 bears with its edge 19 against the correspondingly designed air conduction housing 7 so that no cold air can arrive at the air ducts 8 and 12 the flow path of the warm air coming from the heater 4 and additional heater 5.