disco1994

Hi I have an issue with my car and part of it is that the auxiliary cooling fan isn't working properly. On most cars if you shut off the key and it is still too hot then the cooling fan will still come on. On my 1997 A4 it does not. Does anyone know what controls this function of the fan? Please help.

turbo510

I don't have a schematic available right now, but dont' believe that these early A4s are designed to "after run" the electric fan- my '96 never did. That fan typically is turned on either by a radiator switch, or by the aircon controller. You say the fan "isn't working properly" because it does not run after the key is shut off. How about right before you shut off the engine- is the fan running at that time? If you have overflowing coolant from the expansion tank, which I assume from the word "Overflow" in your thread title, then maybe you have the common broken pump impeller.

disco1994

I was afraid of that. I already replaced the water pump. the one i pulled out was metal and so was the new one I put in, the gasket was leaking though, so not a total loss. My new plan is to replace the secondary auxiliary fan relay, and engine fan clutch.

Adrian Santiago

Did you ever find the problem? Mine keeps blowing the 40amp fuse. for the fan.

disco1994

This particular car has multiple problems. Then engine is very worn and really should be gone through and reconditioned; however, I think that my problem can be band-aid-fixed with a new secondary-speed auxiliary fan relay, and a new engine fan clutch. You may want to look for a short in the wire somewhere near the fan, but I don't know much about the wiring for the auxiliary fan.

Good luck.

Bryans12v

Well if the car is overheating there's another problem. It shouldn't have to use the secondary and should be able to keep itself cool with the clutch fan. I too have overheating issues.

The switch that control the Elec fan is on the lower drivers side of the radiator. Its a three pin switch. Brown is ground, center is low speed and last is high speed. Worst case you can bypass the switch and wire in a fused toggle switch. It can all be done harness side.

Is you lower radio hose

Bryans12v

Well if the car is overheating there's another problem. It shouldn't have to use the secondary and should be able to keep itself cool with the clutch fan. I too have overheating issues.

The switch that control the Elec fan is on the lower drivers side of the radiator. Its a three pin switch. Brown is ground, center is low speed and last is high speed. Worst case you can bypass the switch and wire in a fused toggle switch. It can all be done harness side.

Is you lower rad hose cool when the system is hot?