I have yet to see the fan come on at all ever (but you may be right in that it is on and I don't hear it.) Except when I disconnect it from that control module, then it defaults to the 'on' position, runs just fine. I have previously installed a new thermostat, so I'm pretty sure coolant is flowing. I was thinking of running it at idle until it got up to a 'hot' temp, just to see if I could witness the fan engaging or not. I'd think a new temp sensor would be next? Not sure, planning on hitting the TMs soon. It does not run hot during normal, on-road operation. And finally, yes, that is Maxi- self-declared owner and protector of the Hmmwv! She loves that truck, I can't turn it on without her charging from wherever to get in and go!