Audi Repair: Audi AC fan on at startup and continuously thereafter, thermal switch, engine temperature

Question
Good day;
I saw your post on this problem, and am experiencing this on an '01 A6 2.7T.  If the problem lies in the lower radiator thermal switch, how do I locate, test, and/or replace that switch?  Is this in fact the switch that initiates the electric fan to turn on?  I did confirm that if I turn the AC off (by engaging the "Econ" setting), the fan turns off.  Thanks for any assistance!

Answer
Hi,
I'm not sure if it is the same switch; in fact I doubt it.  You may also check the engine temperature coolant sensor.  If the engine is hot, then this switch would keep the cooling fans running no matter where the AC control is set, so there must be a secondary sensor which determines that the AC fan is activated.  I am travelling without access to my wiring diagrams at present so cannot double check; sorry.  Let me know if you find something,  Jan