My 2000 Chevy Impala A/C only works on the #5 Setting. Since the blower turns on, I know that the problem is not with the blower motor, and that I must be getting the required 115Vac, so it's not the HVAC. I also do not think it's a fuse since I checked them and I'm still getting power where I need it. As best I can tell, the problem must be a short in the wiring going into the blower motor resistor. I replaced the resistor everything worked as it was supposed to, then after a few days, I was back where I started. My best guess is that a short in the wiring is causing an over-current condition which is burning out the resistor pack (blower motor resistor). I'm on this forum looking for a wiring diagram of the applicable components so that I'm not "easter-egging" this problem. Thanks for any help provided.

 

I think your resistor pack assembly is defective. I replaced mine because I lost 2 of the speeds the first and the second. The new desing resistor pack is better insulated than the original which could get damaged by water and short circuits. What a pain to change this resistor block. You need special short tools in order to get at it.