electric problems??
 

Ok so I've been having problems with my 2006 audi a6 quatto. When i have on the ac all of a sudden hot air would start blowing, a couple times iv gotten in the car and i would have to turn on and off the car (sometimes wait) for the interior light to come on, and a couple months ago I was driving and all of a sudden the car just cut off but before it cut off the front window went down on its own. the car sat in the yard for a few months as i was sure it was an electrical problem. eventually a mechanic came and picked the car up. all he did was charge the battery and when he looked at the computer he didn't find any codes or could find anything wrong with it. Could this be an electrical problem that the system is not picking up. Also the back interior light is not working could that be a electrical problem too or do i just need to replace the lamp. Please and Thanks.