Auxillary Fan not working?
 

Hi everyone and thanks to anyone that can give me some insight into whats going on here.

I am the proud owner of a 2001 A4 quattro AWD with 55k.

Bottom line is I'm not sure if the secondary(electric) fan is coming on or for that matter, when it should be coming on in the first place. From the research I have done, it seems that it only comes on when the A/C is activated. So here's the situation:

Yesterday, I noticed the temp guage was fluctuating 1 1/2 ticks above center. I had the A/C on moderate temp and was in stop and go traffic in 85 degree weather.

During this time, the temp coming out of the vents would fluctuate, but only as the temp guage neared the 2 ticks above center. Then it would go down a tick and the air would continue as normal.

So when I got to my destination, I popped the hood to see if all was O.K. My coolant was bubbling, but just a little, barely noticeable. I looked to the secondary fan as I expected to see it come on to help cool the radiator, but that was not happening.

I then leaned as close as I could to it and noticed this little, barely audible, "eeeeeeeeeee" noise like something was resisting. I pulled the 40A fuse out and put it back in and this "buzzing" stopped.

Any Ideas?

I think that if the fuse is fine and it isn't coming on, you need to get a new fan in there... pretty common if I remember.

You can try sending power/ground straight to the fan and see if it comes on and go from there. I unplugged it (on the driver side of the bay, just follow the wires) and stuck some wite into the plug and touched the wires to my battery (I didn't have a muli-meter or anything at the time). Mine came on... I then went to the fuse (mine was blown).

If I remember, the fan should be on all the time and increases speed depending on the conditions.... the hotter it is, the faster it's spinning (faster at idle since there isn't any airflow from driving). I think it comes on even if your ac is off (not 100% sure on all of that though). I would start by sending power and ground to it at the connector (or any other way you see fit). If it turns on, you have some other wiring/electrical issues... if it won't come on with direct power and ground, you have a bad fan motor and need to get a new fan assembly.

Good luck and welcome to the forum :)

Thanks for the info. Assuming it is the fan, how hard is it to replace? I have experience in older cars with more clearance but it looks tight in there. What should I expect to pay for the fan?

Here's one that I looked up... not sure if it's the right one for your car, but it gives you an idea of price.
http://www.ecstuning.com/Audi-B5_A4-...ng/Fan/ES1693/

Or you can go to your local autoparts store and pick one up (most likely a universal fan) for about $70.

As far as replacement, I am thinking worst case you need to put it into "service postition" (you can google this and see how it's done).... Here is a link for installing a front mount intercooler that briefly shows how to put it into service position (somewhere in the middle of the writeup)... (it's not on an 01 though). I haven't looked at mine to see how it is mounted, you might be able to access the lower part of the bracket if you remove the lower shield.... not sure though, good luck.

Auxillary fan fuse location, panel removal
 

I hate to jump a three year old post but I have isolated the problem. AC works fine at speed but blows hot at rest. Auxillary fan is not working. I can energize it so I know it's good. I'm thinking the fuse is bad. From what I understand it is up under the steering wheel.

I can see a black panel there with a light in it and the VAG hook-up but I cannot see any fasteners to remove it.:confused:

I need some guidance on how to get at the fuses and relays.

Thanks,

It could be the fuse, or fan control unit.

To access the fuse, there are 4 8mm screws to remove. Two of them are just on the edge of the panel where it switches from your interior color to the black panel you're referring to. The other two are behind the plastic plugs just below the beltline trim. Use a plastic putty knife to remove the plugs and then undo the screws. There may or may not be one more behind the fuse panel cover. I cannot remember.

If the fuse checks out, the next candidate is the fan controller. It is actually a PWM circuit that controls fan speed. The box is located on the driver's side frame rail just behind the black plastic radiator panel. It should be visible from underneath the car if you remove the belly pan. I may actually have one of these in my spare parts pile if you need one or need a picture of what you're looking for.

fan control unit
 

Thanks for the info. I found how to remove that panel and you are correct. 4 bolts, two hiding behind trim just below the belt line, one on the lower right and one in the fuse panel up on the side of the dash. The fuse is good. I will go to the control unit next.

Could a bad coolant temp sensor cause the problem? I've got a new one just in case.

If you can snap a photo of the controller that would be great.

The fan temperature switch is separate from the coolant temperature sender for the ECU and instrument cluster. The fan switch looks similar and is located in the lower radiator hose, just behind the radiator.

If the fuse is good, I would think that the temp switch is okay because the A/C head-unit can override the switch signal and turn on the fan when the car is stationary. You can test the switch by unplugging it and jumpering the pins in the harness, which should turn the fan on if the control unit is okay.

fan temperature switch
 

Then that will be my next step. Off comes the belly pan. Gah! If I get to do anymore work on my back this week.:p Just got done with the transmission filter and oil.:D Smooth.

Remember that we work on these cars because we love them.