Licoln LS cooling woes

Cooling fan runaway troubles...

Scotty, my friend has a 2003 Lincoln LS with the V8 (made by Jaguar we are told). She took it in for a cooling system flush, paid over $350 for it (needed new thermostat and serpentine belt...stat was 93 bucks for the part), and now the cooling fan sounds like a jet trying to take off. What would cause that...cooling fan sensor gone bad? Seems quite a strange coincidence that this should happen immediately after leaving the shop, and in the winter in NW Florida! Didn't even get to 60 yesterday. Your thoughts?

either sensor is bad or clutch itself has gone out. those are pretty much money pits at that age