you say you cooling fan is working, is this the radiator fan you talking about? if so, is the interior heating fan working(blowing hot air)? if not then it could be air in the radiator.,
Check the radiator and see if there is any oily looking stuff in there, if there is then this would usually mean headgasket.
Also check the oil filler cap for whitish goo, this is also a sign of head gasket failure.,.,