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Thread: Fan Control

  1. #1
    Join Date
    Sep 2015
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    Cleveland, QLD
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    Default Fan Control

    Hi All,

    Audi A4 B7 (Dec 2007) Manual Quattro (83,000klms)

    My Original proplem has been the Air Con cutting in/out. Had a aircon guy come out and advised me to get a second opinion (and quoted nearly 2k to replace the compresor).

    A different Air Con guy came out, he said he could repair the the compressor, but that wasnt the problem. The fans are not coming on to cool the compressor, its probably the Fan Control Unit.

    The A/C fan comes on slowly for a moment then goes off.

    The car hasnt at any time over heated.

    When i'm on the highway the aircon works, however the engine temp gets to 90 degrees quickly and stays there.

    When i run the car with the aircon off, the engine runs cooler around 70-90 degrees, it also takes more time to get to temp. It does get to 90. The fan must come on as the temp drops as you would normally experience, although when in the garage, leaving the engine running i havn't noticed the fan/s coming on.

    I must say i have not noticed the fans coming on for a while, (no over run/fan noise).

    I have replaced the Fan Control Unit, but no change.

    Any help would be greatly appreciated, or if anyone knows a good Auto Electrician in Cleveland/Brisbane who really knows their stuff that would be good too.

  2. #2

    Default

    Have you read the codes from ECU?

  3. #3
    Join Date
    Sep 2015
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    Cleveland, QLD
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    Default

    Hi Tom,
    i have scanned with 2 different makes of scanner, with no codes found.

  4. The Following User Says Thank You to Gasmanphil For This Useful Post:

    DirkOz (January 5th, 2018)

  5. #4

    Default

    You can check if fans are in working condition by applying direct battery power into fan connector.
    Can you hear compressor kicking in /out? You should be able to measure if power is going to the compressor connector.
    Is there correct level of air con gas in the system?
    If possible use VCDS Vag to scan Auto HVAC group.
    System is not letting you to start aircon so there should be codes.
    Check if you have high pressure switch in the system or not. If you have you should be able to measure resistance. Google part number and check what correct result should be.

    I'm not electrician, but have worked on my own car air con systems same way. System is quite easy and it's possible to check every component before buying new part.

    All the best,
    Tom

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    DirkOz (January 5th, 2018)

  7. #5
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    Sep 2015
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    Default

    Will try the fans althought the engine temp does drop when driving without ac on, the ac does work when at speed, it cuts out at high pressure, gas is all good.

    Would you know if the compressor controls the fan?

  8. #6
    Join Date
    Dec 2013
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    Default

    Maybe the first thing to do is work out why the car runs at 70 - 90 degrees with the aircon off. Is it just a dicky gauge, sender or is that the real temp. Might be a new thermostat required before you go further. As a general rule, the condenser fans are on when the AC is on. As you have replaced the fan control unit, I'd suspect that the signal to the control unit is missing.
    C5 RS6: Sportec, Milltek & Wagner -- B5 RS4 : tastefully modified -- Audi 1.8 quattro 132 Kw -- UNIMOG 404 TLF8

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    DirkOz (January 15th, 2018)

  10. #7
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    Sep 2015
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    Default

    the 70-90 is when the fan/thermostat opens(?), anyway im a bit over it now, time to bite the bullet and take in to a local specialist who i didnt realise did this kind of stuff!, fingers crossed....

  11. #8
    Join Date
    Sep 2015
    Location
    Cleveland, QLD
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    Default

    Took car to BPS Autos who did a full diagnostic check, faulty fan, they also did a full check over, finding the things i was suspiciuos of, changed timing belt and water pump and accociated pullys. was happy with pricing too.

    www.bpsautos.com.au

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