Valeooscope - Air Conditioning System Thermal comfort loop

The air extractors are made up of rubber membranes that act as valves. They open to let the air out of the cabin, then close again when the vehicle is at a standstill to prevent the outdoor humidity from ente- ring the cabin. Air extractors can be located: g At the rear of the vehicle (behind the bumpers) g In the wheel arches g In the bodywork at the rear (in the quarter lights) g In the centre pillar (on some 3 door hatchback applications) 9.4. Re-circulating the air We have already seen that the air inside the cabin must be renewed. However, under certain condi- tions it may be important to isolate the cabin from any ingress of air from the outside. This is what the re-circulation system does. Re-circulation consists of reusing the air inside the cabin while preventing any outside air from entering the cabin. The role of the re-circulation system is to: g Allow the occupants to isolate themselves from the outside when in polluted environments g Quickly converge towards conditions of thermal comfort when starting the system (this last feature is generally not known by end users)

The re-circulation flap

The recycling function is located just after the HVAC air inlet

The re-circulation status can be fully open, fully closed or a mix between fresh and internal cabin air. But the re-circulation can only be used for a limited length of time, or the windows may mist up and the occupants may suffer from a dry throat and eyes. On automatic A/C systems the re-circulation flap is controlled by an actuator. For maximum comfort the re-circulation function can be combined with an Air Quality Sensor. The re-circulation actuation must be very reactive to avoid pollution entering the cabin.

Air exhausters

21