If the fan on the inside of the radiator passage side is and aux fans and come on when the ac is on it never come on and my ac get very cold so I think your wrong the fan on the outside of the radiator cone on when ever I turn on my ac and when I turn it off it goes off . Does anyone know for a fans what there 3 fans does ?

My Audi A6, 2.7 does the exact same thing. I am on the forum to get an idea before I take it in to the shop.

2000 A6 2.7T I'm on the same boat

I know this is an old thread but I"m having the same issue. The aux fan doesn't turn on. I have new water pump, thermostat, coolant.. So I'll search the forums for the aux fan issue..