I had similar observation. I was told that the fan has a engine mounted sensor that turns it on and off but like you, it never came on though I have never attained temp over 206. The technician installed a on off switch on the console next to the drivers seat below near the Allison pad. Why he chose to do that instead of trouble shooting or replacing the temp sensor is beyond me but now if I see that the temp is over 200, I hit the button and turn on the fan which I have never had to do. On the plus side, after driving on a hot or warm day, and I decide to park and go to bed, I turn on the fan and it cools the engine and engine compartment faster therefore the bed is cooler faster. Before that, going to bed with engine heat still being transferred to the bed was quite uncomfortable. Kinda like sleeping on a electric blanket in the middle of summer.