First post. I'll apologize in advance for how long this is going to be but I'm beyond frustrated! Here's the deal. Have a 1992 GMC Sierra K1500 that I'm trying to get going again we have had since new and been a farm/ranch pickup. Let's just say it's been abused to the limit and needs a ton of work. It has a manual transmission, which I dearly love for farm work, and I've tried to find another used one like it but have had no luck. So I thought I would get this one at least somewhat reliable again. First things I did was oil change, filter change, plugs, plug wires, and all fluids topped off. Good so far. Then I changed all the lights since only one was working. So far ok. Then started in on the AC. This AC hasn't worked for years but I thought I would try to trouble shoot it. Cleaned the evaporator and condensor then bought a couple cans of R134 to charge the system. Compressor would not cycle so I jumped it of the low pressure switch on the dryer with a paper clip as I read on the internet. Compressor cycled, filled the system up got air temp to 47 degrees and things seemed fine. Plugged the low pressure switch back in the dryer and nothing. Did some research found that this can be a fairly common problem. Decided to take that switch off and inspect it. Plugged it back in. Still nothing. So I jumped the compressor again and went to the cab to look at something. Here is where the fun starts. I started hearing a loud buzzing sound from what seemed like behind the tape deck area. Then all the gauges went haywire and the HVAC controls blanked out. I thought to myself dang did the jumper wire touch something metal? Went to the hood and it didn't appear to be touching anything. I have checked all the fuses and nothing is blown. Here's where it gets even weirder. When I take the courtesy light fuse out the HVAC comes back on but when I turn the fan on it goes nuts, however the gauges work. When I put the fuse back in the overhead light works but at about half power. I have no power to windows and locks and when I depress them the gauges go nuts. The headlights work fine. Vehicle starts and runs like normal. Again no fuses I can see are blown. I am at a loss. I am not real good with electric stuff and I can't really afford to take to a shop as this pickup isn't worth much! Just trying to get it going to use around the farm again but not sure what the heck I may have done. Spent hours working on this thing and feel like it might all have been wasted! Any ideas to try???