Nissan Repair: radiator, radiator fans, radiator cap

Question
should my radiator fans always be on? currently i go to school in flagstaff, arizona were the highest the tempature gets is in the high 70's. i went home to phx and my cars tempature said it was over heating but when i stopped in was cool. is this normal is my car just trying to adjust to the heat again?

Answer
William,

Sounds like your thermostat needs replacement.  I would get one from Nissan since they are superior and go with a 50/50 mix of antifreeze and demineralized water.  Do not back flush the block as it will blow the heater core and get a new radiator cap.