Car is a 1997 A4 Quattro, Engine code AFC:
Coolant temps were reading above normal when stuck in stop and go traffic and the electric fan wouldn't kick on at 92*C. Temps were fine at normal speeds. I thought I had this diagnosed to the coolant fan control thermal switch not activating the electric fan. Unplugged the connector and placed a jumper across pins 1 and 3. This caused the fan to turn on. The jumper between pins 1 and 2 and 2 and 3 did nothing. Feeling confident that the fan does in fact work, I replaced the thermal switch in the bottom drivers side corner of the radiator. Now, I have no heat, and the fan still won't turn on at 92*C. I figured I may have introduced and air bubble into the system when replacing the thermal switch causing my lack of heat. I bled the system the only way I know how which is opening the bleeder hole on the hose that runs next to the battery. My Bentley says to open a bleed screw below the expansion tank, but I could not find what they were talking about. So, I just bled at the location by the battery. A significant amount of air did come out as I lifted the expansion tank up as recommend in another post here. Once coolant came out, I slid the hose back on, and started the car. Still no heat, still no fan. A few questions:
1. Did I properly test the electric fan?
2. What measuring blocks do you use to monitor the coolant system with VAG-COM? Specifically, the coolant fan control thermal switch? I'm currently using 001.
3. Why do I still have no heat? How could relacing this stupid sensor f-ck up the thermostat?
4. I remember reading a post about sometimes needing to bleed coolant at the waterpump to remove all air. Can someone discribe what to look for? I'm not seeing anything.
5. Maybe this is dumb, but you dont need to bleed, start the car, shut off the car, allow it to cool, then bleed again do you?
I'm at a loss. Any help would be apprciated very much.

 

Is your 40Amp fuse blown? Its beneath the drivers side knee bolster.

I had very similiar problems with my electric fan, it would never come on and the fuse kept popping when I replaced it. When I applied direct power the fan operated so I assumed it was ok.

HOWEVER, the fan was operating inefficiently, generating heat and blowing the fuse. See, the electric fan can 'look' ok but actually be going bad.

IF the 40Amp fuse is blown you need to check your electric fan. The way to check for this is the apply direct power and after a minute or so put your hand on the fan body, if it is warm or hot your fan is going bad and you need a new one.

I replaced my electric fan and everything magically fixed. The old fan spun up and ran but it generated so much heat in the circuit it would blow that fuse in seconds. It got progressively worse, at first it would run for 15 min then blow the circuit and over about a month it dropped down to about 30 seconds of useful life before the fuse went.

 

40 amp? Don't see any 40's. Highest is 30. You are talking about the fuse panel that you have to open the drivers side door to access right. Thats the only one I know of. If I'm looking in the wrong place please let me know.

 

There is a plastic panel beneath the steering wheel that runs all the way across. It drops out with 3 bolts and under there you have banks of fuses, your steering linkages etc.

This is independant of the fuse panel.

If you can't find it let me know, I will try to find a picture.

 

Checked all 30's. Nothing was blown. Placed a jumper across the connector and ran the fan for approx. 1 minute. Motor was slightly warm. According to siberian, this could be the culprit of the fan not turning on. I would like to find this fuse so I can confirm it. Need directions to this 40 amp. If anyone can discribe its location please do.

 

Sit in the drivers seat.

Now, imagine you had a glove compartment on the drivers side, beneath the steering wheel. Thats the knee bolster.

It covers the bottom of the steering wheel etc on the drivers side, it drops out with 3 screws that are covered by pop-out panels.

 

Got it! Figured out what you meant before I read your last - but that is a perfect description for anyone else that goes looking in the future.

I found 3 40A - what look to me to be relays. Now, how do you test these things with a multimeter? The positions are: 10 in the upper pannel, and 2 and 4 on the bottom row. None of the three show any cosmetic signs of damage, ie no burn marks, or discoloration.

 

I just pulled the fuse out and checked if it was popped or not. it was hard to tell, no burn marks but they did pop.

This is on my '01 A4, yours may be different, not sure..

 

I bet there is a slight difference. I think you got me pointed in the right direction though. Thanks. Hopefully someone can chime in on the setup on a '97.

Still need to figure out why I don't have heat.

 

I think I'm getting somewhere with why the fan isn't turning on. Anyone want to take a shot as to why I don't have heat?