TAURUS - AC Blower only works on HIGH? High or Off are only options for me...

POSSIBLY your control switch, but likely it's your heater resister block. Not sure if this is a dealer only item or not.

Common on fords to burn the wires off at the resistor too - so may need a new plug (likely no longer available from Ford - so a scrapyard part)

In addition to the things already mentioned, it could be the blower motor itself. I've had them with the brushes so worn that they only speed where they got enough power thru the brushes to fire up was high speed.

Possible, but excedingly rare occurrence. You would generally get s chatter, or it would start on bumps.

BIGGEST problem on Ford the last ten years has been wiring connections. (at least on mine - it's 13 now and has had more connector failures than any 2 other problems combined (vaccum leaks and suspension have been the other 2 issues).

I have a 2003 Taurus. Here was my real problem: when the plastic molding on the outside of the car at the bottom of the windshield on the passenger side would warp, rain water gets on the resistor block and the heater motor. If I remember right I replaced both through the glove box opening or from inside the car. First the resistor block, then a few weeks later the motor died. I then had the Ford dealer install their Ford retro fit kit that corrects the rain water problem, it drains the water differently than the original molding did.