Why doesn't a Nissan truck run smooth in overdrive?

Fan going into overdrive in a nissan titan?

• if im like stopping for just a sec and not turning my truck off when i get out and shut the door its like its tellin me not to leave or somethin cuz theres like a fan that kicks into overdrive in the engine & its really loud and quite frankly kinda embarrassing i think its possesed but it doesnt do it if im just sittin in it while its runnin. only if i get out and leave it runnin. & it only does it when im stopped never when im moving. its an 08 5.6LE & its a V8 its spectacular i lovee it :) except when my fan growls at me! is it normal or is it somethin i need to get checked?

• Answer:

  Engine turned cooling fan and condenser electric fans don't care if you inside the truck or outside they both kick in when radiator temp comes up or the A/C is turned on. When the truck is over night cold check the coolant level in the tank. I suspect it is really warm or hot when this truck growls at you and that might be normal.