just started doing this today in my 2000. Storm was coming in and I put the windows up. After the brief but intense downpour, I went to get something out of my truck and the blower was on high. Did not think too much of it, as my key will pull out of the ignition in any position, I thought maybe I was in too much of a hurry when I put the windows up. But NOPE, it was in the lock position. Put the key in, rolled ahead to the run spot, rolled back to lock and the blower went out. Weird, I thought, went to get out and the blower came on again, along with a lot of relay clicking from the center area of the dash. So, I turned the blower off.

Would this be a faulty and incredibly worn ignition switch ? It is the original, or is there something else more deep rooted here.

 

Talking about rain makes me worry the windshield is leaking and getting the GEM wet. When the GEM shorts out you get all kinds of odd electrical gremlins, so this would be the first thing I would look out.

The ignition switch (electrical part) and lock cylinder (part you put the key in) are separate. You can adjust the switch a little, the blower motor should be on the ACCY circuit. The rod may not be moving the switch far enough to disconnect power on the ACCY circuit would be my second guess.