Audi Q7 2007 Repair Manual page 65

matic air recirculation" is present the compressor is also
switched on when outside temperatures are smaller than 2° C
(36° F). Compressor operation is not possible with tempera‐
tures lower than approximately -8° C (17.6° F).
♦ At setting "automatic air recirculation" on the Climatronic Con‐
trol Module - J255- front A/C control head or in MMI (Multi
Media Interface), compressor can be switched on also by
switching on recirculating air manually (via "recirculating air
button") up to a temperature of approximately -8° C (17.6° F).
♦ To ensure that the A/C does not operate constantly in the re‐
circulating air mode in areas with a consistently higher pollu‐
tion, the sensor is self-adapting (it adjusts its sensitivity to the
environmental conditions).
♦ If outside air pollution load remains high for longer period of
time, the sensor starts to adapt itself to the changing environ‐
mental condition through an adaptation program (learning
program), the air recirculation request in evenly polluted am‐
bient air is therefore generally shorter than 12 minutes. If a
succession of peaks in the polluted air is detected, the air con‐
ditioning system can operate over a longer period of time in
recirculated air mode.
♦ A certain amount of time is required for repositioning of the air
conditioning system doors. In the event that a sudden increase
in pollutants is encountered (for example, when driving
through a diesel exhaust cloud) gaseous pollutants can be
taken in with the fresh air into the passenger compartment until
the doors can be closed. For this reason, a dust and pollen
filter is installed with a charcoal layer. A filter that is saturated
with pollutants is no longer effective and needs to be replaced.
Refer to
⇒ "9.36 Dust and Pollen Filter with Activated Charcoal Filter
Unit", page 170
♦ In order to avoid frequent shifting of the recirculating air/fresh
air doors, a slight increase of pollutants in the ambient air will
not allow for immediate shifting (the sensor does not send a
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
request to the Climatronic Control Module - J255- front A/C
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
control head). The filtering of the charcoal insert in the dust
with respect to the correctness of information in this document. Copyright by AUDI AG.
and pollen filter will be sufficient. Refer to
⇒ "9.36 Dust and Pollen Filter with Activated Charcoal Filter
Unit", page 170
♦ In order to avoid frequent shifting of the recirculated air/fresh
air doors, the requirement from the Air Quality Sensor - G238-
sensor for "Automatic air recirculation" mode remains for at
least 25 seconds (minimum duration period), even if the pol‐
lutant concentration is so far reduced that recirculated air
mode is no longer necessary.
♦ If the compressor is shut-off (for example, in "Econ" mode),
the maximum duration of the "Automatic recirculating air
mode" is limited to approximately 15 seconds by the Clima‐
tronic Control Module - J255- front A/C control head to avoid
windows from fogging up.
♦ So that fogged windows are cleared as quickly as possible,
the Climatronic Control Module - J255- front A/C control head
does not permit recirculating air operation during the "Defrost"
operating mode.
♦ After the ignition is switched on, Air Quality Sensor - G238-
requires approximately 30 seconds to be operational (warm-
up time). During this time there is no requirement from the Air
Quality Sensor - G238- to the Climatronic Control Module -
J255- front A/C control head for "Automatic recirculating air"
mode.
♦ The Air Quality Sensor - G238- contains a highly sensitive
electronic component which can be damaged if it comes in
Heating, Ventilation and Air Conditioning - Edition 04.2013
.
.
5. A/C System Control and Regulation Components Outside Passenger Compartment
Audi Q7 2007 ➤
59