HOW DOES A HVAC SYSTEM IN THE CAR WORK?

HVAC (Heating, Ventilation and Air conditioning) in the car is designed to maintain the temperature in the car cabin and also provide fresh, filtered, quality air on a constant basis. Depending on the outside temperature, the supplied air is either heated or cooled (chilled).

The quality and temperature of the surrounding air strongly influence a driver's performance and concentration. Therefore, the cabin air filter is a key part of the air ventilation cycle. To ensure that the interior of the vehicle receives clean, fresh, quality air, it is strongly recommended that a cabin air filter be installed in the air intake duct of the blower in order to filter foreign particles such as pollens dust, soot, etc. from the outside air.

A schematic diagram of a HVAC system is shown above to illustrate the arrangement in the air intake.

 Fresh, Quality air operation
Outside air is drawn through the blower fan. The air grill blocks large matter and particles eg. leaves and insects. The cabin air filter is installed in the air duct prior to the blower fan, it filters industrial pollens dust, fungus spores, bacteria, soot and other unwanted particles before the filtered air reaches the condenser.

Here it is cooled to a lower temperature, causing water to condense and be removed to the outside via run-off tubes. Subsequently, the dry, cool air is warmed in the heat exchanger to the interior compartment temperature selected by the driver. From there it passes through various mixing doors and openings to the desired locations in the interior car cabin.


Recirculation mode
In this mode of operation the air mixing door is fully closed right after the outside air enters through the air grill, the air is drawn solely from the vehicle's interior. After passing through the cabin air filter and condenser, the filtered air is then returned to the passenger car cabin. This mode of operation is used mostly in traffic jams or when driving in tunnels.