Well, I am an A/C Engineer with Carrier Air Conditioning. Stop the bickering. Below 40 deg. (in the car temp) the A/c compressor doesn't come on. Air below 40 degree. has less than 10% rel. humidity when heated to 70 deg. However, the A/C will dehumidify when warmer and is useful for that.
Having said that, CHOICE is BETTER. If you like it, turn it on, if you don't like it, turn it off. EASY.
I am going to look at wiring diagram and try to figure out the crazy wiring diagram Ford has in manual. I suspect there is an output right on the floor/def/vent etc. selector knob or on the vacuum actuator linkage that tells the pcm the knob is in def or floor/def. Check with a VOM and I bet you can fake out the pcm and tell it the knob is in def or out of def, without going under the hood.
However, for me, under the dash is nearly as bad as under the hood. Too many things, not enough room.
I miss my '64 Impala. You could have a party behind the dash and no A/C, No PCM, an upgraded 35Amp alternator and 2 (Two) speed auto (Powerslide errr,,I mean Powerglide) tranny. Really got that 283 CID V8 power to the ground, eventually.
