Just drove to lunch and romped on it a little bit to see if I could hear the fan noise you are describing. I got nothin but engine and exhaust noise. My truck isn't modded yet so they are stock noises.
This NISSAN has some incredible power--it's funny to let my girlfriend drive and to feel her totally LUNGE the truck forward when she hits the gas pedal...cause she's so used to having to mash down her wimpy car's gas pedal. When only a touch of the Frontier's pedal is needed. LOL.
I'm glad to have one of the few remaining engines that actually has a belt driven fan. I figure most these days are plastic electric motors--BUT NOT MY NISSAN!!!!! Woot!