I purchased my 2004 Ford Thunderbird last fall. He had owned it 11 yrs. I had read about the overheating problems owners have had. My temp gage started to climb to 3/4 and it was making me nervous . The previous owner had just replaced the Air conditioning condenser before I bought it . He gave me a printout from the Ford dealership of everything that he had ever done to it. One of the last service dates was for the cooling fan running on high all of the time. Internet forums like this one are wonderful for finding information . I took it to a shop I trust and this is what they found. I don't know all the tech lingo but here I go. There was this valve that has 3 hoses to it, one going to the heater core that was cracked. Its toward the top of the engine so it has to be warmed up for it to leak and loose pressure. That was replaced. Then they put all new hoses on it. Then a coolant flush and all new coolant added. They put the vacuum test on it and found it still not pressurized right. One temp on one side of the Thermostat and another on the other side. They replaced the Thermostat. Everything is running GREAT !. No more fan coming on high and not shutting off and the Temp gage is right in the middle. The car is so quiet running now that I never knew the exhaust note sounded so nice when you get on it a little. I hope this might help others out there. I know looking at other posts helped my mechanic .