I can feel that fan come on and suck power out of the engine at dumb times, like anytime the engine is below 2000 rpm or something, or when the engine is trying to warm up. I'd like to have a switch that turns the fan off when I don't need it, especially during winter here where it gets down below zero a lot. And I only work a few miles from home so the truck is already difficult to get up to temperature often enough. Is there like one little wire on the fan clutch assembly that I can put a switch on, and it makes the clutch never engage?

 

A fan clutch doesn't have any electrical connection so there's no way to "switch" it. It operates on thermal expansion and engine speed. Are you sure what your "feeling come on" is not the AC compressor? The compressor doesn't just run when you have the AC on, it works when you have the defrost or vent heat on as well and will kick on and off as needed.

 

+1, no, not possible

 

yup AC kicks in every vent position except face only and i think floor only. Every other position it kicks in regardless of temp **** location.