S4 V8-4.2L (BHF) (2004)
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Activate windshield wash/wipe switch until Windshield Washer Pump V5 has conveyed fluid for approx. 2 s.
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Read off display in zone "4".
Specified value:
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"30" ("Recirculated-air mode" requested because of windshield washer system, air conditioner switches to recirculated-air mode for approx. 10
sec.)
NOTE: The request for "recirculated-air mode" during windshield washer system operation is not implemented with all versions of the operating
and display module, Climatronic Control Module J255.
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Wait briefly.
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Read off display in zone "4".
Specified value:
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"00" (no request for "recirculated-air mode" , air conditioner in fresh-air mode)
Or
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"60" (Partial recirculated-air mode)
NOTE:
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Depending on the composition of the windshield washer fluid, the Air Quality Sensor G238 may detect air pollution and request "Automatic air
recirculation".
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If switching to recirculated-air mode does not take place on activating windshield wipe/wash switch, check operation of Wiper/Washer
Intermittent Relay J31 if applicable ("windshield wash" information is received via the CAN-Bus comfort system from the Steering Column
Electronic Systems Control Module J527 ) (Reading measuring value block, display group "018").
Proceed as follows if the Air Quality Sensor G238 functions properly in this test but a customer complaint has been received:
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Check for contamination of dust and pollen filter.
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Connect Diagnostic Operation System VAS 5051A for example and select function "08 Reading measuring value block" for air conditioner.
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Enter display group number "014" and read off displays in zones "3" and "4".
NOTE:
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A second person is required to read out the values displayed while driving.
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Pay attention to safety precautions.
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Perform a test drive, starting in an area with a relatively clean ambient atmosphere (system operating in fresh-air mode) and then proceeding to an
area where the atmosphere is polluted (e.g. uphill road with truck traffic).
NOTE:
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The display in zones "3" and "4" in display group "014" must change, for example, on driving through a cloud of diesel emissions. See:
Testing and Inspection/Scan Tool Testing and Procedures/Measuring Value Blocks (Function 08)
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Also pay attention to the notes on the dust and pollen filter and on operation of the Air Quality Sensor G238.