2000 Ford Taurus coolant tank overflowing

Start with the cooler fan, you say it's not working? Also the cap on the bottle may be NG, if it doesnt hold the 16lbs of pressure, it will overheat, and you have overheating confused with a blown head gasket, if you get white smoke from the tailpipe, it's a blown head gasket! The heater cores on these are famous for clogging, so make sure the coolant level is right, and check the two hoses that go into the core, they should both be hot. If one is cold, the core is clogged, and needs to be replaced, I havent had much success flushing these out. Cooling fan and temp sensors are VERY important fix these first!