[V6-12v] Radiator Fans not working

Tom Christiansen tomchr at ee.washington.edu
Mon Sep 20 22:45:28 EDT 2004

The fan speed is controlled by a thermal switch located on the starboard 
side, bottom of the radiator just above the drain  plug. I forget how many 
speeds the fan has but I think it's three. The different speeds are set 
with a resistor pack located on the port side sub-frame. It's pretty easy 
to find if you trace the wires from the fans. It looks like an L-bracket 
with a couple of wire taps on it.

So there are a couple of possibilities for failure:
1) The fans themselves.
2) The two relays driving the fans: The one at position 18 (high speed) and 
the other at position 11 (low speed).
3) The resistor pack.
4) The thermal switch.
5) Fuses S15 (25 A) and/or S42 (60 A).

The fan is supposed to run at full speed when the A/C high pressure switch 
engages. I would assume it does so when the A/C is running. The fan on my 
1994 90S normally turns on at low speed when the temp gauge reaches about 
straight up (whichever temperature that is).

If you click "wiring diagrams" in the Bentley manual, then select your 
model year, and select "manual climate control" you should be guided to 
page 102 in the manual. It has the relevant schematic.


At 05:06 PM 9/20/2004, T. Jackson wrote:
>I noticed this morning while sitting in traffic that my car was running a
>little warmer than normal.  After a while the traffic cleared up and I
>started moving so the car temperature stayed nominal until I got to work and
>forgot about the abnormal temperature reading.  On the way home after
>sitting in traffic I noticed my temperature gauge slowly approaching the
>120C mark while my oil temp was around 130C!  I managed to get the car
>moving again and cool enough to pull over and check the fuse box.  The fuse
>seemed to be in good shape and the label on the box indicated that it is
>shared with other items like turn signals and wipers which all appear to be
>working.  Before continuing the drive on the open road I did a quick check
>to see if there were any disconnected wires or harnesses and I couldn't see
>any.  It was much too hot to go prodding in the engine bay so I saved myself
>the potential 3rd degree burns and I will take a look at it in the morning
>when it's much cooler.
>Does anyone have any ideas as to what I should be looking for?  Is it
>feasible to test the fans by applying 12V from the battery to the connector
>(where ever it is)?
>BTW, the car is a 1995 Audi 90 Quattro.
>V6-12v mailing list
>V6-12v at audifans.com

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