radiator fan running constantly in cold weather..!

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Feb 14, 2011 | 10:17 AM

amicus

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radiator fan running constantly in cold weather..!

Ok, so my radiator fan is acting up. I've been trying the narrow down the sources of the problem and I suspect it might be the fan switch causing the problem.

On my 1993 90s the low speed fan automatically turns on when I turn the ignition on (from a cold engine) and when I turn the engine on, the fan comes on high speed. It never turns off only if I pulled the key out.

It's definitely not a cooling problem. So I checked the run-on relay in the aux. relay box (under dr. side dash) and it's not stuck. I also pulled the cable to the fan switch (on the radiator) and my fan turn OFF.

So, I guess, my question is, is it really my fan switch that could be causing this?

I am about to order a new one, but I would really appreciate any help to confirm. Thanks in advance!

Feb 14, 2011 | 10:22 AM

CRAZY_RUSSIAN

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From: Reno, NV

is your AC off?
and if so, its sounds like thats the problem

Feb 14, 2011 | 10:36 AM

amicus

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thanks, yea the a/c is off.

actually, a couple days back my a/c button didn't light up when pushed in but now it is lighting up and I hear the compressor turn on when I engage it. But it is definitely in the off position and my fans are still running.

I think I'm going to go ahead and order the fan switch. Now that you mention it, though, could it be a faulty a/c (climate button) itself causing this problem?

thanks again.

Feb 14, 2011 | 10:52 AM

CRAZY_RUSSIAN

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From: Reno, NV

not likely... give a new switch a shot. i dont know when the last time you flushed ur coolant, so i would do a coolant flush with ether G12 or G11 (i use G12 in my)

Feb 14, 2011 | 05:34 PM

hubturn

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From: Charlotte, NC

Just to make sure the fans are operating properly, and since you pulled the connector on the fan switch, run a jumper from the center position of the connector to first one of the other contacts and then the other. One side is low speed, and the other side is middle speed (IIRC), center is power. That way you know nothing else is screwed up. There is a thin cardboard-like flat washer that should be included with the new switch. You could replace it without draining the radiator if you move quickly. That's what the Audi dealer mechanics told me to do. Just an option, but maybe not a good one though.

Mar 8, 2011 | 06:13 AM

alburnsy

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Im having the same Issue with a %1 plate Audi A4, from a cold start the radiator Fan engages at high temperature even without the engine kicking over.

The garage has repolaced the Coling sensor but this has not helped.

To add to my frustration the Cooling temp guage only works when the car is stood still, if you drive the car anywhere and for a hour or so the temp guage does not move at all it only moves when the car is stationary.

Any Ideas would Help great as this is costing me a fortune at a garage.

Mar 8, 2011 | 12:41 PM

hubturn

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From: Charlotte, NC

Sorry, you lost me. What's a %1 plate? If this is a 2.8l, there are 2 sensors called temperature sensors. One goes to the temp gauge in the instrument cluster, the other sends intelligence elsewhere. Also a fan switch and several relays. Did an Audi dealer work on this? Did whoever did the work pull codes and what were they? Which sensor did they replace? From the tone of your post I believe you've figured out that knowledge is power, particularly when you get presented with a bill. Go to www.12v.org and study the system and search the forum here for more info. Then you'll know if you are being hoodwinked by a parts changer instead of someone who can diagnose a problem. Let us know how this works out.