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Radiator fan comes on and runs at full speed when heating is switched on

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by keenu, Jan 22, 2014.

  1. keenu

    keenu Member

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    Hi,

    I have an Audi A4 2002 and it has recently developed an issue with the radiator fan coming on as soon as I switch the heating on. When I switch the heating off again the fan stops. Any ideas what it could be? The fan seem to be running at full speed as well.
    This happens even when just starting the car and turning the heating on from cold.

    Thanks
     
  2. kite

    kite Member
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    You have 2 fans. 1 is for the air con the other for the engine.
    If you have your heating on and press the econ button does the fan stop.
     
  3. keenu

    keenu Member

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    Thanks, yep there are two fans in front of the radiator and both come on when the heating is switched on and run at full speed. I haven't tried the econ button but i can give it a go when i get home to see if it makes a difference.

    Could be a linked to a coolant temperature sender issue? I had an issue where the coolant temperature would fluctuate and not stay at 90c.
     
  4. quattrojames

    quattrojames Moderator
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    On my A6 when the CTS was knackered it kept the cooling fan on permanently.
     
  5. kite

    kite Member
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    Change the CTS and go from there.
     
  6. keenu

    keenu Member

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    Cheers, I didn't know if the two issues were linked, just seems strange that it happens when ever i turning the heating on and any other time its fine. I guess it must be some sort of sensor issue.
     
  7. pauldazzle

    pauldazzle Active Member

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    Fans are supposed to come on when the AC switched on.
     
  8. keenu

    keenu Member

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    Hi,

    Well I changed the CTS (the green one) which is located at the top of the engine and it made no difference. The fans do go off when press the ECON button. I read there is also a 2 pin grey CTS that connects to radiator. Can anyone tell me where it is? Does that apply to my Audi A4 2002 model? Thanks.
     
  9. pauldazzle

    pauldazzle Active Member

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    If the fans go off when you press econ, it's working correctly.
     
  10. keenu

    keenu Member

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    But I never had this problem before, as in I never used the Econ mode before and the fan wouldn't come at all when the heating was switched on. Its only been happening in the last couple of weeks. I have owned the car for 4 years now.
     
  11. pauldazzle

    pauldazzle Active Member

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    It isn't a problem. With the AC on (Econ light off) the fans are supposed to come on to cool the AC system. With the Econ switched on the fans should stop.
     
  12. keenu

    keenu Member

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    Just in case anyone has this problem it was to do with the fan control module, got that replaced and it fixed the issue.

    The fans never kicked in when stopped at traffic causing the engine to overheat and when turning the climate control on they were running at full speed (Note: there not meant to be running at full maximum speed, they are only meant to turn on slightly!)
     
  13. tom2

    tom2 Member

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    On mine, 1.8t, there is a temp sensor at the bottom of the radiator, on the right hand side (if standing infront of the car). Right next to the drain tap. Hardest part of changing the bottom one is getting the belly tray back on.

    I'm having similar issues at the moment, I didn't realise there was a temp sensor at the top of the engine... Is this the case with the bex engine? If so anyone got a pic of where?
     
  14. keenu

    keenu Member

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    Don't have a pic but it is just below the top of coolant reservoir.
     

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