Electric fan woes
 

Hi guys I'm Mark, I stumbled across this place looking for some help with this issue I'm having - looks like a wealth of info!

I believe the issue lies somewhere in the electric cooling fan circuit. Initially the alternator went seemingly because the fan control module went. I have replaced both of these and I'm still having problems. Since the fix the battery is being drained - a 5A load! I also noticed a humming coming either from the electric fan or the FCM. This humming happened with the car off/cold engine for a good 15 minutes until I disconnected the battery.

This is as far as I've gotten. I suspect it's the fan because of the humming and the load - but I can't understand why it would be running for so long after the car is turned off and the engine being cold. That makes me think there's a bad sensor/relay causing the system to stay on and drain the battery - but then I can't understand the humming.

Any ideas? Should the fan come on for longer than 15 mins on a cold engine? Also, what exactly does the FCM do?

I'll take a jab at this. I know on my 1999 A6 the electric fan only comes on if the coolant tempature gets too hot or the air conditioning is turned on it's automatic as the other mechanical fan is for primary cooling. If the fan is staying on that long that would be the problem probably a relay stuck open that's what I would check first. I would check the entire fan circuit and see where the problem is.