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Thread: fan fail light

  1. #1
    Junior Member
    Join Date:  Jun 2017

    Posts:    12

    fan fail light

    Hi

    Is it normal for the fan fail light to flash on briefly every time the air con compressor engages ? Fans come on and run ok its just accompanied by the light for a brief moment and the clicking from the relays behind the seat. Do I need to buy the kow amp draw replacement fans ?

    Thank You

  2. #2
    Senior Member Bitsyncmaster's Avatar
    Join Date:  May 2011

    Location:  Leonardtown, MD

    Posts:    6,877

    My VIN:    03572

    Normally the fan fail unit has been removed and replaced with jumpers (as per recall notice). When that is done the fan fail light is not connected to anything. The original fan fail unit would turn on the fan fail light if the current of both fans dropped below 20 amps total. So assuming your still running the original fan fail unit, your voltage probably drops when the AC kicks on and therefor your fan currents drop for an instant.

    Now I have found when the AC kicks off there is a negative 200 volt spike that can get into the cars wiring and that has upset the voltage regulation in some alternators (and can cause other problems). Putting a diode or zener diode on the compressor clutch will remove that negative spike.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  3. #3
    Delorean Guru
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    To answer that question it is helpful to know what is in the fan fail relay socket. The quick answer is NO, the light is not supposed to go on unless you have a relay in that socket that works and there is a problem with one of the fan motors. I would also verify none of the bulbs were mixed up in the console and it isn't the fan fail light lighting up.
    David Teitelbaum

  4. #4
    Junior Member
    Join Date:  Jun 2017

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    Quote Originally Posted by David T View Post
    To answer that question it is helpful to know what is in the fan fail relay socket. The quick answer is NO, the light is not supposed to go on unless you have a relay in that socket that works and there is a problem with one of the fan motors. I would also verify none of the bulbs were mixed up in the console and it isn't the fan fail light lighting up.

    Blue relay in the fan fail socket. Both fans work as far as I can see but I do want to replace them with the new style fans.

  5. #5
    Delorean Guru
    Join Date:  May 2011

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    You really should not be using that relay. Very high failure rate. Probably the reason for the flickering light.
    David Teitelbaum

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