A motor vehicle cabin has four seat positions and a heating and ventilating apparatus which includes means for producing hot and cold air streams, temperature control means, air distribution ducts having outlets at different points in the cabin at each seat position, and distribution means for adjustably distributing the mixture of the cold and hot air streams between the various air distribution ducts. These ducts include ducts which are open in at least two different points in the rear seat positions, each of which has its own temperature control means for adjusting the air temperature at that position, and means for adjusting the flow of air to that position.