Thanks Josch,
I was afraid it would be complicated, and it sounds like it is. The reason I want to turn on the fans is just to keep the engine cool while I am in slow traffic, or stopped. The fan is not turning on until the gauge is at the top of the L. The car does fine when I'm at highway speeds, with the gauge staying at the R-M. I've given up on Ford being able to fix it, and I'm trying to figure something out myself.
