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Thread: Aux Cooling Fan troubleshoot?

  1. #1
    Join Date
    May 2006
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    NH
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    Default Aux Cooling Fan troubleshoot?

    I was greeted the other day by myaproximately One year old Made in Germany Aux Cooling Fan suddenly going at High RPM the moment I turned the Key to Position #2 when about to start the car. The air temp at the time wasn't even 90 F.

    I removed the radiator sensor plug to jumper and see what was up. I got High but no low rpm.. when I jumper the Low wire I hear the Relay clicking but the Fan doesn't spin. Is the Resistor failed? I actualy went and bought a brand new relay from BMW but may not have needed it. The wires in the relay box leading to the low speed relay all appear intact but I haven't used a volt meter or ohm meter to check anything . oh and the two fuses are OK. Any ideas?
    Last edited by Jehu; 07-28-2010 at 08:38 PM.
    1995 540i Manual build 1/95

  2. #2
    Join Date
    Apr 2008
    Location
    Illinois
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    123

    Default

    Quote Originally Posted by Jehu View Post
    I was greeted the other day by myaproximately One year old Made in Germany Aux Cooling Fan suddenly going at High RPM the moment I turned the Key to Position #2 when about to start the car. The air temp at the time wasn't even 90 F.

    I removed the radiator sensor plug to jumper and see what was up. I got High but no low rpm.. when I jumper the Low wire I hear the Relay clicking but the Fan doesn't spin. Is the Resistor failed? I actualy went and bought a brand new relay from BMW but may not have needed it. The wires in the relay box leading to the low speed relay all appear intact but I haven't used a volt meter or ohm meter to check anything . oh and the two fuses are OK. Any ideas?
    Yeah, it's possible! Check the Resistor and the low speed supply.

  3. #3
    Join Date
    Oct 2004
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    Honolulu
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    3,105

    Default

    Got a meter?

    check to see if the resistor is fried... Had the same thing a while back and it made me for a day trying to figure it out


    Vee ave vays of dealing vid your kind...........

  4. #4
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    Default

    Thanks gents. I can get a meter and may be just source a replacement resistor and splice it in and see anyway.
    1995 540i Manual build 1/95

  5. #5
    Join Date
    Feb 2007
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    GreenHills East-Philippines
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    Default

    Quote Originally Posted by Jehu View Post
    Thanks gents. I can get a meter and may be just source a replacement resistor and splice it in and see anyway.
    had a similar problem too 2 weeks ago turned out to be the socket of the aux fan was not making contact so i cleaned it. Was brittle too and whenever the fan turns high mode socket becomes abnormally hot so im looking for a replacement socket.
    Last edited by bmwrp8; 08-06-2010 at 01:09 PM.

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