THE AUTO COOL GUY's web site is bad...he really needs someone to redo it and rewrite everything. his PWM controllers are interesting if that's the style of controller you want. HERE'S the instruction pages. setting the "ON" temp basically involves using a heat gun and setting the on temp, measured at the radiator outlet, ~ 10' below what your thermostat opening temp is. that sets the "ON" temp, and the controller ramps the fan speed up and down using that for a base line
