Device and method for controlling air temperature for a vehicle air conditioning system

The air treatment system for a car heater has two chambers (1, 1') in each of which two streams of air (A, B, A', B') of different temperatures are mixed before being fed on as a combined stream of uniform temperature. One of the streams (A, A') enters each chamber via independent self-closing non-return valve (2, 2'). The other streams (B, B') enter via directly controlled valves (5) which are linked. An independent claim is included for a method for treating air, for use in a car heater.