GM-GMC: 2001 chevy silverado, Heating & AC, chevy silverado, voltage spike

Question
I own a 2001 Chevy silverado for about 1 1/2 yrs.  Some kind of problem with htg & A/C.  If I stop vehicle while switch is on heat and start short time later it will be stuck on heat and can't switch to AC.  It also does this vice versa.  If the truck is stopped long enough for the temp gauge to go down I can sometimes get it to AC.  Also once this past winter when I put it into 4 WD, there was a quick power surge, then i could not switch from defrost to vent, change heat coming out or turn down the blower until I Stopped and restarted.  I live in Duluth, MN so in a matter of minutes I can be using heat and then ac because of the lake effect.  i would appreciate and help and advise.  Thanks Dave L

Answer
thats verry odd. the only thing i can think of is that there is a problem in the electronics, maybe a bad module (computer) that controls the a/c commands. knowing that there was a power surge this would be my guess, the modules are very sensetive to voltage spikes and are easely be damaged by a voltage spike. i would recomend taking it to a dealership to have it further diagnosed. wihtout further testing i couldnt come to a conclusion.