If you're running with a tail wind the fan will come on more than if you are going into a head wind. You wouldn't think so, you would think the engine wouldn't be working as hard, and that is true but the front of the truck then is in an area that is almost a vacuum (especially when towing a big box behind you that is taller and wider than the truck)and the fan will be required. (18 wheelers are the same way, I used to drive one). Running into a head wind the air is kinda being forced in but even then sometime the fan is needed. An a/c evaporator core puts out lots of heat and then the intercooler also adds to the heat load, something you didn't have on a gasser unless you had a turbo or a blower and these Fords don't don't have much room under the hood for the air to flow thru. That's why they put the fender vents on the new one's. Dry heat doesn't feel as hot to us people as humid does but to the truck it is hotter and altitude makes it worse because the air is thinner. Pulling my toybox up the high passes in Colo. the fan will be on, even when the temp is down around 40 F. I agree though that listening to the fan gets old on a long trip. Mine will be off 5 minutes and on for 15, then off for 5 and on for 15. 06 F350 6.0 dually fx4 pulling a 40 ft. toybox.