tricky1090

I'm assuming my problem is the fan control module. The left electrical fan (when facing the car) never spins, and the right fan (on outside) runs in hyper-mode when the AC is on (shuts off in 'econ' mode). I also noticed today that the right fan kicks on as the after-run fan (again, in hyper mode). I thought the left fan was after run? I can push the left fan and it spins so either fan motor or fan control module?

rodhotter

on my new 01 TT 225Q i have yet to see any fan run, the afterrun coolant pump comes on, thats it. i replaced coolant sensor with a green top, temps have only reached about 70 since purchase in dec 11, temp guage starts at a quarter and goes to 5/8, summers comming we will see i guess, sure does not seem right

ezveedub

Your passenger side fan is most likely dead. The front fan is now doing the work of both fans and is running like a banshee to keep up. You have to send power to the passenger fan to see if it works or not. If its blown and you don't replace it soon, the front fan will also burn out.

ezveedub

You have to check the fuse panel on top of battery. It has a 3 wire connector and three fuses. They are notorious for melting at the fuses or connector. If they are fine, make sure the other fuses on it are OK also. The green temp sensor you replaced has nothing to do with the fans, that's the ECM & temp gauge sensor. The fan switch it located in the radiator on the driver's side. It has three wires. The solid red wire is positive power. If you bridge the red solid wire with one of the other wires on the connector, the fans should run. I believe the center wire is speed 1 and the other wire is speed 2. Key needs to be on. There is also a fan module located on the lower chassis leg below the battery. That module can also blow, but usually the AC doesn't work when it does.

tricky1090

I tested the passenger side fan and it's dead. I got a replacement and plugged it in, but it didn't kick on. When exactly should this fan kick on? My other electric fan (driver side) runs with the AC. Is the passenger side one just the after-run fan if the engine is too hot? Also, I looked at the timing belt DIY to see the service position. Do you need to get the car in full service position to replace that fan, or is there a point where you can just slide the front forward a few inches and replace it that way?

ezveedub

The passenger fan is supposed to run at the same time and at the same speed as the front fan. It has a small screw you remove at the top and then rotate it and it should unlock from the radiator support. You just have to pull the wiring out from all the clips attaching it to the front radiator support and then install the new one. I have to look up the wiring to see if there's maybe a separate fuse for each fan, but I know the wiring coming to the fan control unit seems to be single wiring and then splits up to each fan, which makes me thing there isn't a separate fuse, but I'll have to check to make sure.

MonroeS4

Probably needs new brushes for the fan motor, I just did them on my 2000 S4. Quite hard to find. I found most Audi fans from 90s up are basically the same PN with different suffix. The brushes are mostly the same so you can get a fan motor from a salvage yard that runs and swap the brushes if the fan configuration isn't exactly the same.

tricky1090

Thanks for the updates guys. Turns out it was just a bad fan, picked up a replacement from the classifieds and installed. It didn't kick on on my original test. I tested it again and after a minute or so of the car and AC running, it kicked-on. Still not certain what conditions cause this fan to operate, but it seems to be working.

rodhotter

a scan by a knowlegable VCDS operator can determine most issues, i stopped in my favorite tuner shop APTuning Lebanon PA, for about $50 i had my answer, a bad relay, fans only ran on lo speed, its better than throwing parts at it, sometimes you are lucky but electrical stuff is usually not returnable so a simple diagnostic is worth it, stealers will kill you, find an honest independent shop