Air intake control system in air conditioning system

Claim 1

In an air conditioning system having an air intake system adapted to be switched between at least an outside air position and a recirculating air position, an air intake control system comprising: (a) a pressure activated actuator adapted to switch said air intake system between said two positions; (b) a mode selector having two inlets receiving a first control pressure and a second control pressure, and, adapted to supply selectively a plurality of different groupings of said first and second control pressures to said actuator; (c) a first reference pressure source supplying a first reference pressure; (d) a second reference pressure source supplying a second reference pressure; (e) an air control switch receiving said first reference pressure source, adapted to output said first reference pressure when operated; and (f) an air intake changeover switch receiving input pressures including the first reference pressure from said air control switch, and said first and second reference pressures from said first and second reference pressure sources, and adapted, in a first position, to supply a first combination of said input pressures to said inlets of said mode selector; and adapted in a second position to supply a second combination of said input pressures to said inlets of said mode selector; wherein said second combination is such that irrespective of the switching state of said mode selector, the groupings of said first and second control pressures supplied to said actuator is such that said actuator switches the air intake system to said recirculating air position.