My primary cooling fan is never turning on, and my secondary if only tuning on with the AC on. Do these two fans share the same power wires? If so I have to assume that its not a wiring problem. Also, I have to assume its not a fuse/relay problem because if it was the secondary fan would never come on. I do not think the fan is dead, because the smaller fan works with ac, but neither work when AC is off. It is leading me to think that whatever turns the fans on when the car is up to temp is not functioning. Let me know what you guys think, Thanks in advance!

PS, my climate control cluster is showing it staying at 90 even when gauge climbs past middle during city driving.

 

one the fans have separate wiring. I agree you say the larger fan is not coming on but the small is when it is hot enough or when the a/c is used. So, it could be a fuse the one one top of the battery there are 3 the left one I believe is used for fans check to see that it is good it pulls out easy and you can tell if it is apart. I do not believe it is the aux. fan controller as many times it is that bottom line I believe your motor for the big fan is gone if you have a tester guess at a number 1157 like a battery tester to show juice is getting to it it is just along the radiator on the bottom the just above the lower hose radiator connection two plugs one is for big one and one for small one take bottom pan off to get to can get through the top but must be small

good luck L8R........

 

the secondary fan only comes on when the ac is on, never triggered by coolant temp. I got a chance to jack it up yesterday and I disconnected the primary fan and checked the connection and there is not power. I have checked the fuses and relays and they are all good. I am thinking that it is the Radiator Fan Switch? Do these go bad? do they control the fans functions?

 

yes the aux. fan controller is a big problem in audi & vw but normally both will not turn on ..... when you unplug the larger fan you tested the end from the engine to the fan shroud? or did you check the end in the fan shroud?

if no power was being received from the engine side into the fan shroud then it could still be a fuse.. if you check the one in the fan shroud check the other one. fuses on top of battery 3 of them and check your owners manual for the fuses inside the car I will look as well.

NOTE: if I am asking you like dah/ no **** sherlock questions it is I do not know your level of mechanics as mine is very limited at times so please do not take offense....

 

I'm having the same problem...
The passenger side fan is working when my engine temp reaches its point.
The larger fan does not come on with or without the A/C on.
So is the larger fan work in conjunction with the A/C Drivers side
Or does the smaller fan work in conjunction with the A/C Passenger side?
Anyone?

 

Ok! I pulled the fuse in the dash #16 10a and both fans turned on asap.
I then put the fuse back and ran the A/C and both fans came on asap.
So i'm thinking it's the unit control module for the a/c the one under the battery...
both fans work, For some reason just for that day the drivers side fan did not come on..weird...
Electrical short somewhere...I will change the module though.
Caught one on Deutsche Parts for $54.99...so not bad...

 

on this product Deutsche Parts for $54.99 off ebay it is a coin toss may last a long time or a week or so as it is not the exact part I hope yours works forever

but did everybody check their fuses on top of the battery makin sure they we not blown?







CHECK THIS AS WELL GLAD IT IS WORKING

http://WHANAB.COM/

 

Yes, I changed those awhile ago and I checked again, all are fine..
Today the large fan did not kick on again after I replaced the fan switch yesterday.
So unit contol next then the large fan...

 

replacing the switch is fine but it could easily be the fan motor and it is and was on its way out... now is gone.... that is an item that can be bought off ebay and should do fine.. I had thought you had replaced the aux fan controller my
mistake.... but with the small still working it still can be the aux fan controller as it has a 4-pin 16-pin set up half only working??

you are covering all your possibles take care

 

Ok! Yes, the control module will be easier to change out than the larger fan.
I will prob change the fan as well, since its 9yrs old.
good thing for this forum, I did not know of the Control Unit Module!
Learn something new everyday about my TT..