Dust And Pollen Filter With Activated Charcoal Filter Unit - Audi Q7 2007 Repair Manual

Audi Q7 2007 ➤
Heating, Ventilation and Air Conditioning - Edition 04.2013
– Remove the dust and pollen filter -C- from installation com‐
partment of the A/C unit -A-.
– Clean installation compartment of dust and pollen filter -C- of
the A/C unit -A- (for example, using a conventional vacuum
cleaner) of leaves, dust and other contaminants.
Installing
– Check installation compartment for soiling, clean via installa‐
tion compartment of the A/C unit if necessary.
– Insert dust and pollen filter -C- into compartment of the A/C
unit, while doing this pay attention to the direction of flow (ar‐
rows on filter -D- point toward evaporator).
– Check seal on cover -B- for damage.
– Install cover -B-, ensure proper fit in mount while doing this.
– Install the remaining removed components again in reverse
order.
9.36 Dust and Pollen Filter with Activated
Charcoal Filter Unit
♦ Vehicles wit the "Basis" and "Comfort" A/C systems have a
dust and pollen filter with an activated charcoal air filter. Ve‐
hicles with the "Comfort" A/C system also have an Air Quality
Sensor - G238- .
♦ The activated charcoal filter element functions as a dust and
pollen filter, however in addition the activated charcoal filter
can also filter out gaseous pollutants, for example ozone, ben‐
zene, nitrogen dioxide from the air flow.
♦ On vehicles with a "Comfort" version A/C system, the task of
the activated charcoal is to absorb gaseous contaminants in
the air flow for as long until the A/C system switches over to
air recirculation mode (fresh air/recirculating air door seals the
fresh air intake channel and opens the air recirculation intake
channel). The change over from fresh to recirculating mode
occurs via the Climatronic Control Module - J255- front A/C
control head, as soon as the Air Quality Sensor - G238- de‐
tects gaseous pollutants in the ambient air (the "automatic air
recirculation" mode must be selected).
♦ On vehicles with "Basic" version A/C system, the task of the
activated charcoal is primarily to absorb gaseous contami‐
nants from the incoming airflow when contaminant levels in‐
crease (and then possibly to emit the contaminants again
slowly). If filter is saturated, it permits gaseous contaminants
to stream in freely.
♦ The activated charcoal layer in the dust and pollen filter reacts
differently to various pollutants in the air.
- Certain pollutants bond permanently in the activated charcoal
layer.
- Others are converted into innoxious bonds as in a catalytic con‐
verter.
- For the rest the activated charcoal works as a condenser (ca‐
pacitor). With load increasing, pollutants are absorbed for as long
until a certain saturation point is reached. If the amount of pollu‐
tants decreases, the activated charcoal layer continuously relea‐
ses 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 ac‐
tivated charcoal layer.
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Rep. Gr.87 - Air Conditioning
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