My climate control unit sometimes resets on my 2004 A4 quattro 3.0. All the lights on the unit blink off, fan stops blowing and then returns to the original correct setting. Took it to the dealer a few times but they tell me there is no record of the event in the error logs. It's a random event.

 

You need a new A/C control head, you can't replace this yourself without a VAG COM.

 

VAG-COM Locator-
http://vag-tool.kicks-***.net/