i was messing around with making my own controller for a bit to run my electric fans.
I was gonna build a controller to use a PWM relay, by varying the ground to the relay, i could control fan speed so i could ramp it from 0 to 100% depending on engine coolant, a/c high side pressure (i had a pressure switch off a jaguar for this) and vehicle speed.
I stuck the fan clutch back on instead since i ran out of time and was really busy at work.
I lost 1 mpg with my modded low temp fan clutch.