Fusing the fan?

Ben Swann benswann at comcast.net
Tue Sep 21 20:18:07 EDT 2004


The fuse as done by the factory is installed in the brown wire - when I installed the one on the 5000, I was simply copying what was done in my '91 200q 20v.  So the Audi engineers are wrong?  There are ate least 3 positive wires supplying current to the fan, also, which would require several fuses.  Lets review to make sure this is correct.  

I agree that normally devices are fused on the positive side, but I think if you look at how the motor is constructed, etc. the return to ground makes the most sense, although hypothetically, some internal short in the fan could possibly occur, but would also need that the fan motor is not rubber isolated and some other coincidences for there to be a problem.

  ----- Original Message ----- 
  From: Robert Myers 
  To: Pat Korach ; Hoffman Anthony J A1C 552 CMS/MXMVC ; 'Ben Swann' 
  Cc: quattro at audifans.com 
  Sent: Tuesday, September 21, 2004 10:58 AM
  Subject: Re: Fusing the fan?

  NONONONO!!!  A fuse should always act to shut off power to the protected part of the circuit.  Put it on the "hot side" of the circuit. If a fuse on the ground side of the fan blows there will still be a nominal +12 volts supplied to the fan.  If the fan is short circuited to ground - first there is no protection and second, it's unlikely the fuse will even blow because the current drain will flow directly to ground bypassing the fuse.  It would not matter a whole lot whether the fuse blew or not under those circumstances.  How good are you at fighting electrical fires?  

  At 07:51 AM 9/21/2004 -0700, Pat Korach wrote:


    If I remember right you fuse the brown ground wire going to the fan.

    Pat Korach
    Kirkland, WA

    ----- Original Message -----
    From: "Hoffman Anthony J A1C 552 CMS/MXMVC" <Anthony.Hoffman at tinker.af.mil>
    To: "'Ben Swann'" <benswann at comcast.net>
    Cc: <quattro at audifans.com>
    Sent: Tuesday, September 21, 2004 4:17 AM
    Subject: Fusing the fan?

    > How have some of you fused the fan? I have two 5000's recently acquired,
    > would like to do this. What amp rating is required?
    > As a side note, I put the battery under the back seat of my 4kq, no design
    > flaw there.
    > Tony Hoffman
    > _______________________________________________
    > quattro mailing list
    > quattro at audifans.com
    > http://www.audifans.com/mailman/listinfo/quattro

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