Electrical problem

The column mounted switch has a short wire harness made onto it. There's a white connector to the cars harness under the dash. These connectors have melted and crossed circuits. Doesn't explain why the radio isn't involved though... unless there is more than one hot in run buss bar in the later model fuse boxes. That wouldn't surprise me.
There's another harness connector out there in the engine bay near back of right rocker cover that also has a melt down history. It's white plastic also. A crossed circuit and back feed there would light up some circuits. To power blower, wipers, etc.. at once when back feeding through these smaller wires will do more harm. I would visually inspect those known culprits first.