Abstract: A heat exchanging unit for motor vehicles, having a first heat exchanger that has two headers that are situated parallel to one another and at a distance from one another and that are connected to one another fluidically via a multiplicity of connecting pipes situated parallel to one another and at a respective distance in the longitudinal direction of the headers, the connecting pipes opening into the first header asymmetrically with respect to the width of the pipe floor situated perpendicular to the longitudinal first header axis, and the second wall segment, in the cross-section regarded perpendicular to the header longitudinal axis, becoming increasingly further removed from the first end of the pipe floor as the wall segment extends towards the second end area of the pipe floor, regarded in the direction perpendicular to the longitudinal axis of the connecting pipes and perpendicular to the longitudinal header axis.