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Engine fan coming on immediately

Discussion in 'A3/S3 Forum (8L Chassis)' started by Schlaag, Jan 22, 2014.

  1. Schlaag
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    Schlaag Bwah

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    Hey dudes, if its not one thing its another.

    I noticed when I started the car (S3) this am that the engine fan also came on straight away. quite fast. Could really hear it outside the car.

    also upon stopping and switching off, the fan kept going.

    Its never done this before.

    I've just gone out now while the car is cold and switched on the ignition (not started) and the fan comes on. Switching off the ignition and it remains on (will go off eventually)

    Is this a common problem? anyone had this and resolved it?

    hmmmmm


    thx
    Dave
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  2. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Quick scan for fault codes may elude to an issue but sounds like the fan switch or controller could be an issue...

    Fans are normally on on low speed if aircon is on but high speed normally only kicks in over a certain temp...

    Try disconnecting the switch on the radiator... pretty sure this is used to keep the fans going in high speed should the temp be too high..

    <tuffty/>
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  3. cammage08
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    cammage08 Member

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    Sorry to highjack... Just to confirm both fans should spin when air con is switched on?
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  4. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Should do yeah

    <tuffty/>
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  5. Schlaag
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    Schlaag Bwah

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    Well battery was dead earlier. It seems the fans stay on now when the key is out and stay on until the battery dies.

    anyone had this/got advice?

    ready to torch this car at present
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  6. cammage08
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    cammage08 Member

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    Possible 1 of 2 things.... the temperature switch in the radiator that tells the fans to come on or the actual fan control unit underneath the battery that could possible be faulty?
    #6
  7. Schlaag
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    Schlaag Bwah

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    Hi, thanks. but slight update. Kept an eye on the fans after I pulled up this eve. Went back out after 20 mins and they were off. Ok fine I thought.

    Just now (next day - morning) Battery COMPLETELY flat!

    Its off and on charge then i'll leave to see if it holds charge.....

    Other than that i'm at a loss
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  8. Schlaag
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    Schlaag Bwah

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    Update, it was the fans. They constantly run and dont switch off.

    for the time being i've disconnected the plug to the fan on the lower right of the rad (me facing the car)

    Ive searched loads but it's yeilding results all for 8P cars.

    Would it be a faulty water temp sensor? (dash temp guage is normal and fine)

    Or the actual fan?

    I dont want to buy a new fan assembly, fit it and the problem to still be there
    #8
  9. cammage08
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    cammage08 Member

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    Where you unplugged it from the radiator is a thermostatic switch which i believe tells the fans to switch on/off? Possible at fault..
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  10. cammage08
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    cammage08 Member

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  11. Schlaag
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    Schlaag Bwah

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    Hi mate. I didnt unplug from the actual switch screwed in to the rad. ( i couldnt find it)

    There are two joining plugs on the fan shrowd of the air con fan. One for the air con fan and one for the engine fan. I just seperated the engine fan one
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  12. cammage08
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    cammage08 Member

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    I see... im only suggesting this as i had a dodgy fan situation but it turned out my fan was dead but id looked into it all. Id still suggest this fan switch as its a cheap place to start...
    #12
  13. Schlaag
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    Schlaag Bwah

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    I'll reconnect the fan loom, try to get to the plug on the rad switch and remove. If it kills the fan then I guess thats the fault right there.

    Out of curiosity mate do you have the part number of the fan you replaced? and how much it was? (assuming you have an S3?)
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  14. cammage08
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    cammage08 Member

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    I dont have the part number sorry... I got it from GSF for £54 i think it was.. mine was getting power but it was just buggered and yes its an S3. Try the switch and report back :)
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  15. Schlaag
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    Schlaag Bwah

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    Will do. Sorry another Q.. do you know if the battery tray is removable? if so will help loads as space is tight back there!
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  16. cammage08
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    cammage08 Member

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    Yes im sure it is.. once you remove the battery its just bolted down..
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  17. Schlaag
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    Schlaag Bwah

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    Just a little update. I finally got around to replacing the fan switch! (what a knob of a job that was getting to it!)


    Now, when switching ignition to second position (and starting the car) the fan comes on (left fan if you were looking in to the engine bay from the front of the car) I'm sure this isn't right but hey...

    On switching off the engine, the fan now stops right away. Again i'm sure the fan should stay on for a few minutes then switch off?

    I took the car for a run yesterday up to temp (90deg bang on) then left it parked and idling for 15 mins and the temp remained bang on 90 deg. Didn't stray over at all.

    Not sure if this is all correct as i'm sure the fan shouldn't come on from cold start and that is should remain running for a few minutes after shut down

    But at least the fan isn't constantly running after keys are out, killing the battery!
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  18. Schlaag
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    Schlaag Bwah

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    EDIT! I forgot to mention.. in order to get enough room to remove the fan switch, I removed the pass headlight and boost hose.

    on removing the boost hose bracket, this fell down to the floor( as the bracket mounts to it)

    Now known to be the fan controller module! NOTHING was plugged in to it! and I certainly haven't removed the plugs.

    Guess im taking things apart and looking for the plugs that should be connected to it then!

    $_1.JPG
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  19. cammage08
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    cammage08 Member

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    Looks very much like a fan controller...
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  20. Schlaag
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    Schlaag Bwah

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    Yep sure is mate. Why the hell was nothing plugged in to it though is the question!

    I must admit when I found it at the weekend I thought it was some sort of diagnostics port tucked under the battery but only this AM on some searching did I find out it's the fan controller.

    So the search is on for two rogue plugs to connect back on!
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  21. cammage08
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    cammage08 Member

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    Keep us updated!
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  22. coolspot007007
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    coolspot007007 Member

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    I'm having the same sort of symptoms, battery dying within about 4 days and fans spinning up intermittent with air con off. Don't really want to take loads of stuff off to get to controller, but would give me a chance to paint my hard boost pipes by the FMIC. Can you get at it by removing the arch liner and wheel instead? I've got more space to do that than bumper off.
    #22

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