1990 Sierra 3500 won't hold HVAC Fuse

[MoralDK]

I've got a 1990 GMC Sierra 3500 dually w/454 - Turbo 400. Keeps blowing the 25 amp fuse for the HVAC. I've replaced the blower motor, the resistor and the control head. Each install would get me a day or two of normal operation. Then, the fuse would blow and blow the next one immediately, without hesitation. I'm guessing a bad connection or a shorted wire. Does anyone know of a common problem? Is there a walk-thru to dismantling the dash to get to the wiring behind the scene? It's pretty Rubic to me....could really use some help.

 

[happy 2011]

Frist of all you need a wiring diragram of whats on that fused circuit. Then you need to know how to read it. Next you just dig in and start testing and unpluging stuff till you find it. now it's not hard if you understand how DC volts work but if you don't you will have a hard time. I always say you can't fix it if you don't know how it works.

Good luck