My 03 A6 3.0 is intermittently overheating. I checked the fans and they work when I start the car. In the driveway the temp guage gets up to about half way and the fans go to slow speed and the AC blows warm. I hear a sound by the fire wall that sounds like a valve releasing or something.

I recently had my oil pump replaced and I am now using 0W40. Not sure if this could have anything to do with it.

What should I be looking for? Thanks for any help!!

 

It ended up being the fan control module. So if anyone finds themselves in a similar predicament, make sure to check the fcm.