aux fan short in wire or???? - Mercedes-Benz Forum

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post #1 of 2 (permalink) Old 12-05-2006, 09:06 PM Thread Starter
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Date registered: Dec 2006
Vehicle: 280se 1971 3.5 v8 (m116)
Location: Australia
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Question aux fan short in wire or????

Ok guys have a prob with my aux fan on my w108 /m116 3.5 problem is that my thermo aux fan has a short in the wireing but where? so far I have checked the following:

1. checked the fan by grounding the single (brown with white stripe) all I get is a blown fuse (fuse is near the engine next to bettery)

2. Ok so try the fan on its own (ie) direct 12volt she runs perfect!

3. relay test next swap over relay with csv relay it works, again try csv relay with fan relay's spot same prob, fuse blows!
4. one more thing the aux fan does not come on also when I put the air con on but this could be the fact that the gas is low?

....So can I assume wire problem (ie wire grounding on body but where!!) tried to find a wire diagram but no luck if anyone can scan me a page for the aux fan that would be nice

if this diagram exists i would be greatful?

Anymore tips would be fantastic..thanks guys!

PS - I did notice the fuse is rated 16a (red cermic fuse) could this be too low, the wires look very thick??

Last edited by nrgvision; 12-06-2006 at 07:13 AM.
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post #2 of 2 (permalink) Old 12-07-2006, 11:51 AM
BenzWorld Senior Member
Date registered: Jun 2006
Vehicle: 1981 300CD, 1973 280C
Location: California
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To verify the fuse rating you need to measure the amperage the fan motor uses on start up and while running. Fan motor could be worn enough its pulling too many amps when engaged. 16 amps seems to me to be about right assuming the fan itself is ok. If there was a short to ground then even a 20 amp fuse would blow I would think.
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