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Auxillary fan constantly running?

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Old 08-30-2011, 12:51 AM   #1
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Default Auxillary fan constantly running?

My auxillary fan turns on right after I start the car. It often will cycle on and off every few seconds, but other times it will just stay continuously on while the car is running. This started happenning about 5 months ago. A search revealed the culprit may be the auxillary fan control module. Has anyone else had this experience? Does a faulty control module seem reasonable? VAG scan revealed no codes. Finally, where is this control module located? Thanks in advance.

Paul
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Old 08-30-2011, 11:21 AM   #2
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dude... it runs with the ac ....
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Old 08-30-2011, 02:19 PM   #3
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Originally Posted by 2.7Lturbo View Post
dude... it runs with the ac ....
That's the short answer. The slightly longer one is:

Yes it does...SO, if it's always running when the AC is switched on and sounds like an air-raid siren, yes, it's probably the fan control module. Normally, they fail because the main electric fan jams and the control module blows to "protect" the fan. When the module is faulty, the system commands the aux fan to HIGH all the time when AC is enabled. The main fan normally gets jammed by a piece of it's own trim, which can be easily removed.

If the aux fan is ALWAYS ON - regardless of the AC being on or off, the module may not be the cause.

The module can be purchased at your favorite parts supplier and is a 50% bitch to replace unless you go service position. From there, it's a 10 minute job. Yes, I've replaced mine to solve the problem described in paragraph two.
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Old 08-31-2011, 01:33 AM   #4
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Thanks for the detailed reply. I really appreciate it. The auxillary fan will go off when the a/c is turned off, however the auxillary fan goes on the minute I start the car regardless of coolant temperature so long as the a/c is on. In the past I've heard it go on very rarely on a hot day. Now it is on all the time. I know this is not how it is supposed to be. Thanks for the tips. I will look more closely at the fan to see if it"s jammed.

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Old 08-31-2011, 01:46 AM   #5
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The Aux fan should turn off, functions properly, when ECON button is pushed on or the FAN speed button is pushed down to no bar is seen.
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Old 08-31-2011, 01:52 AM   #6
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Yes, the aux fan does go off when econ button is engaged. Does that suggest the Control Module still may be the culprit of it running non-stop? It is my understanding that when the a/c is on the auxillary fan should come on as needed and not be on the entire time the car is running. Do I have that right? Thanks.

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Old 08-31-2011, 05:05 AM   #7
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Yes, the aux fan does go off when econ button is engaged. Does that suggest the Control Module still may be the culprit of it running non-stop? It is my understanding that when the a/c is on the auxillary fan should come on as needed and not be on the entire time the car is running. Do I have that right? Thanks.

Paul
Yes - you have that correct. It SOUNDS like the fan control module has failed in the "normal" way.

Grab hold of the blade of the back-side fan (with the car OFF, of course). If it will not spin freely when applying finger pressure, it also has probably "failed in the normal manner" and is jammed up by a small piece of rubber trim stock that has slipped. Find the jam, remove it, assure a free spinning blade and the fan is PROBABLY still good. Historically, the control module will fail and "protect" the fan (although I'm sure it can also fail WITHOUT the fan being jammed).

You can then decide to replace the control module or not. It took me one entire season to get around to it and then I only changed it because I took the whole damn thing apart to replace a failed alternator and the old one was right there, mocking me. If you don't use the AC a lot in your environment, the only thing that's being hurt, AFAIK, by the aux fan running full speed is the ears of you and everyone around you
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Old 08-31-2011, 09:37 AM   #8
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You think that's loud! Try having the mainf fan clutch fail in the engaged position.... Sounds like a jet engine everytimei revit, I kind of like it
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Old 08-31-2011, 11:23 AM   #9
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Quote:
Originally Posted by RMsALFA View Post
Yes - you have that correct. It SOUNDS like the fan control module has failed in the "normal" way.

Grab hold of the blade of the back-side fan (with the car OFF, of course). If it will not spin freely when applying finger pressure, it also has probably "failed in the normal manner" and is jammed up by a small piece of rubber trim stock that has slipped. Find the jam, remove it, assure a free spinning blade and the fan is PROBABLY still good. Historically, the control module fails to "protect" the fan (although I'm sure it can also fail WITHOUT the fan being jammed).

You can then decide to replace the control module or not. It took me one entire season to get around to it and then I only changed it because I took the whole damn thing apart to replace a failed alternator and the old one was right there, mocking me. If you don't use the AC a lot in your environment, the only thing that's being hurt, AFAIK, by the aux fan running full speed is the ears of you and everyone around you
Thank you very much! That is exactly the kind of response I was hoping to get.

Paul
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Old 09-07-2011, 05:51 AM   #10
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Default Same on 2003 A6 2.7

I'm seeing the same thing on my '03 A6 2.7.

Aux fan is on full speed when AC is on 'Auto' but occasionally cycles off then back on.

Turn on 'Econ' mode then aux fan stops.

It does not matter what outside temp is or temp of engine.

It did it this morning at 50 deg and a cold start.

Does anyone know the part number for this unit?

Thanks.
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Old 09-08-2011, 12:10 AM   #11
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Electric Aux Fan for 2.7 Quattro with AC P/N
http://www.ecstuning.com/Audi-C5_A6-...gine/Cooling/2
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Old 09-08-2011, 03:54 AM   #12
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8D0959501D - Radiator Fan Controller/Resistor; Control Module for Auxiliary Fan

This is the number I used to order the module for my 2001. I'm not 100% sure if this is a VAG number or Autohaus AZ's stock number. It looks like a VAG number...
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Old 09-08-2011, 06:07 AM   #13
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if you search that number on ECS it comes up, genuine audi and some other brand, but under applications it only says allroad and S4 - any reason why it wouldn't fit a 2.7? i have the same situation as well, but not sure i want to shell out a ton of money to fix it
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Old 09-12-2011, 06:01 AM   #14
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Google and amazon are your friends...

http://www.amazon.com/gp/product/B00...ag=invihand-20

Just a FYI- I called Shokan looking for an used unit and they said there were different PN's for this unit. They would only match a PN that I had. Guess I need to take a look...
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Old 09-12-2011, 08:37 PM   #15
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Please post here if and when you replace the module and let us know if it solved your problem. I have the same symptoms as you are having, but I would like to use you as the ghinea pig
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