re: "...Didn't realize that the 92 and 93 had such differences! On our 92, if the compressor is engaged on ours (no matter how hot or cold), the aux fan kicks in...."

I also didn't know that the fan doesn't always work -- when I got my first '93, I worried (when it came the summer) and the fan didn't come on (that was before I was able to score the '93 Green book on eBay). But soon, on a hot day, it came on, and I realized it was pressure dependent. And when I finally got my Green book, I could see in the diagram (on pg 112, with references to items by letter for anyone else with the book who is also reading this) that there is the pressure sensor (F) as the direct, sole controller of the fan relay (D).

re: "...AC fan relay/fan is fed through the ignition switch...."

I don't remember writing that about the ignition switch. They aren't, at least not directly.

The fan relay's load current comes directly from the battery, via the later '93s' unique array of 4 fuses (H) on the battery's positive terminal, so it's always "hot". But the relay's coil current actually comes from the FI Control Module (214), via the other pressure sensor (J) in the dryer when its contacts close (btw, this 'close' also powers the heater fan to run, even if it isn't turned on with the switch).

All in all, I agree that the fan relay is the best suspect, since it's "live" all the time -- if its contacts stick closed, the fan will run regardless of anything else except pulling its fuse.

By the way, the fan is run off a different fuse (on the positive battery terminal) than the rest of the A/C system. The fan is run by the Blue 20A fuse, whereas the rest of the A/C system is run off the Yellow 60A fuse (see pg 2).

Happy holidays.