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Is that a website where you list your car if your wife tells you to sell your car and you really don't want to?

Yep, that is one of the weaknesses of searches on most forums. If you don't know what the key word is, or how the original post was phrased, it becomes a frustrating exercise. I had to cheat myself and search for my attachments to find one of the relevant threads😎 Incidentally, that part has increased in price quite a bit and you might do better to find a used climate controller since it must be removed to repair in any case. Jim Finn is a good source for tested used parts.

As you know the wires under the driver's side are power and under the passenger are ground. When I was having a self induced electrical problem with my 'vert we ended up pulling the carpet on both sides and redoing all the splices. Kendall [my mechanic friend who did the soldering] said he was surprised I didn't have other electrical issues. Always a good idea to take a look at the splices.

So far you are doing a great job of troubleshooting. I think you are right about S311, but if you could try disconnecting the switches and light connectors that are easy to get to first to rule one of them out being the problem. The more direct route, but a little harder, is to remove the seat and carpet and start with S311 first. When you have it apart (if it's not already rusted apart and grounding the wires right there) you can test each circuit that branches off individually to determine which one is shorted. If you find problems with the splices on that side you should go ahead and do the splices on the other side because they are probably in bad shape to.

So I figured I could mimic Padgett's suggestion by just using my voltmeter plugged into the fuse slot and looking for when voltage drops to zero. Of course it is showing 12.2 or so to start. Finding the wiring diagram for fuse 2 (it is #2 on the '90 as well @Ronnie) I figured I will try eliminating this C200 connector first. It is located on the passenger side down in the foot well I found it and unplugged it and the reading on the volt meter dropped to zero. Next is deciphering this diagram.