Dust and Pollen Filter With Activated Charcoal Filter Unit

Dust and Pollen Filter with Activated Charcoal Filter Unit

• When using the air quality sensor (=> [ Air Quality Sensor Function ] Air Quality Sensor Function) a dust and pollen filter with an additional filter insert with activated charcoal is installed in vehicles with an air quality sensor.

• The activated charcoal filter element continues to function as a dust and pollen filter, however in addition the activated charcoal filter can also filter out gaseous pollutants e.g. ozone, benzene, nitrogen dioxide from the air flow.

• The role of the activated charcoal is to store the impurities in the through-flowing air until the fresh air door is closed and the air conditioning system is operating in air recirculation mode. The change over from fresh to recirculating mode occurs via A/C control head Climatronic control module, as soon as air quality sensor air quality sensor detects gaseous pollutants in the ambient air (the "automatic air recirculation" mode must be selected).

• The activated charcoal layer in the dust and pollen filter reacts differently to various pollutants in the air.

- Certain pollutants bond permanently in the active-carbon layer.

- Others are converted into noxious bonds like in a catalytic converter.

- For the rest the activated charcoal works as a condenser (capacitor). With load increasing, pollutants are absorbed for as long until a certain saturation point is reached. If the amount of pollutants decreases, the activated charcoal layer continuously releases the absorbed particles.

• Under the following operating conditions the dust and pollen filter must be replaced earlier than required, because a certain amount of pollutant particles is permanently bonded to the activated charcoal layer.

- If vehicle is driven in areas with strong air pollution.

- If vehicle is predominantly driven with the "automatic recirculating air" mode switched off.

- On vehicles without the air quality sensor option and therefore without the "automatic recirculation" mode.

• If possible, the A/C system in vehicles with the air quality sensor option should always be operated in the "automatic recirculation" mode. If it is necessary or desired to switch the function off, the following should be observed:

- The active carbon layer in the dust and pollen filter is saturated after a certain time.

- A saturated filter can no longer absorb pollutants and the pollutants can flow through freely.

• The most important task of the dust and pollen filter and air quality sensor is keep the load peaks out from the passenger compartment. To allow this to be effective, the following should be observed:

- If a vehicle is driven in an area with relative clean ambient air (with little gaseous pollutants in the air), the change over from fresh into recirculating mode occurs at different point in time as in an area with high basic load (e.g. industrial area).

- Independently of the basic load, the change-over from fresh to recirculating mode always occurs, when the pollutant-load increases (e.g. when driving to through an exhaust cloud of a Diesel truck).

• The activated charcoal filter can be installed in all vehicles (also in vehicles without the air quality sensor option). The same limitations apply to these vehicles as on climate control systems with the "automatic recirculation" mode switched off.