I have two problems and I doubt if they are connected but...... First there is a short in the electrical system and it is still there even if I disconnect the fuse box from the system, I also pulled each fuse and relay and none of them got rid of the short. Does anyone know which wiring diagram I need to isolate this short. The other problem is that I only have air conditioning in the winter and only heat in the summer.

 

What year, make, 4x4, 2wd? I know it's a 2nd gen because of your other post about the A/C.
That one seems like an electrical issue like something cross wired & not the common vacuum issue, but it could also be part of the problem.
What circuit is the short in, what accessory is affected? We can't help with the short if we don't know what circuit it's in.

 

It's a 1999 4x4 Blazer. The short isn't in any circuit, I pulled every fuse and still had the short, then I disconnected the hot wire to the fuse panel and still had the short. I separated the two connectors coming off the hot side of the battery and the larger red wire is the one with the short. Do you know where that one goes, all I can see is that it goes into the frame to somewhere?

 

It goes to the starter on the PS.
Disconnect the + on the battery NOW & check that FAST! Because it shorting out could very possibly cause the starter to toast if not start a fire!

 

The Pos wire goes into the starter and the neg cable goes on the block or the frame.

 

I keep the neg side disconnected but when I connect it the car starts and runs perfect except for the heater/ac. I can't work on it any more today but I'll get under there and see what the starter looks like. I suppose I should disconnect the pos side too before I quit for the day.