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Radiator fans working sometimes

shaheed Jul 17, 2007

  1. shaheed

    shaheed Member

    My both radiator fans started to work whenever they want.
    Basically even with the engine still cold the fans start to work and stops after a while...it depends how much
    They seem to work in full throttle.
    Audi dealer said both fans need to be changed :(
    Anyone could explain your experiences with it?
    Couldn't that be a module, or faulty temp sensor?
  2. DaveS3Turbo

    DaveS3Turbo Sepang Blue S3

    Hey on my 2.0T Quattro the fans wouldn't turn off even when the ignition was off. After on full whack for an hours or so the battery was flattened.

    They replaced the whole fan module / sensor etc... After it kept repeating itself..


    Let them carry out the warranty work. They take the whole front off to do this.
  3. Staz

    Staz is a retronaut Moderator VCDS Map User

    Could it be the condensor fan for the air con maybe? I'll have a look which is which etc in a bit
  4. wilko

    wilko Top Gear

    Mine sound like they come on as well even when the engine is cold. Was gonna raise it next time I heard it do it - but typically I haven't heard it since. If you find out why it does this please let us no.
  5. Staz

    Staz is a retronaut Moderator VCDS Map User

    Right I've finally had a look under the bonnet and I was right.

    Both the radiator cooling fans also act as the condensor fans for the air con system. They don't work at full speed for this though. They will move into full speed if the engine needs forced air.

    If you want to check if this is what you are experiencing then simply turn off your air con (press the ECON button) and after a short time (depending on how long the system has been running and the ambient air temperature) the fans will switch off. Do this when the engine is cold so the fans aren't running anyway to cool the engine.

    Also this is why the fans continue to run after switching off the engine. I'd guess they run so high pressure liquid is available in preparation for you switching the engine back on i.e. when you get back into your car and switch on the cooling will be there sooner.

    EDIT: Actually the fans stay on to change all the remaining vapour into liquid for safety.

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