I have the aux fan and a Ford Taurus 2 speed fan, I just use the Taurus lower speed for normal driving and stop and go trafic with out any problem, when I use the 4x4 I turn on the aux fan to keep and adecuate temperature and everything it´s been ok! and I still have the high speed of the taurus fan free to be used just in case.( I took off the fan clutch and since I have no A/C I took off 3 of the pulleys that I don´t need with my no A/C set up) :clapping: