Abstract: An air conditioning installation for the cabin of a motor vehicle comprises an air treatment and distribution unit, consisting of a trunk containing distribution valves and a mixing valve, together with a heater. The installation treats fresh air, drawn from outside and/or recirculated air and delivered by a blower, and distributes the treated air into the cabin of the vehicle. The installation includes sensors for periodic measurement of the temperature inside the cabin, the outside temperature and the temperature of the engine coolant fluid. It also includes a setting module whereby the demand temperature in the cabin can be set by the user, and control means for measuring a difference between the demand temperature and the prevailing inside temperature.

Abstract: A motor vehicle air conditioning system includes an adjustable position air inlet valve for controlling the relative proportions of recirculated air and fresh air from outside entering the system. A first sensor and a second sensor give respective measurement signals representing the inside temperature of the cabin and the outside temperature. The occupant of the vehicle can set a required value of inside temperature on a data unit, which memorizing this setting. The installation includes a processor for computing the difference between the actual inside temperature and its required value, and for memorizing at least one first temperature threshold value. The processor makes a first comparison between this first threshold value and the computed absolute value of the temperature difference, and then performs a second comparison between the inside and outside temperatures.