Fans funky, car overheating. Please help
 

I have a 1991 Camry DX V6. It runs like a champ, but the radiator/cooling fan only runs if the AC is on. I tried to disconnect the sensor at the top of the radiator hose, but this did nothing (i was told it would cause the fan to run regardless). When the engine gets hot the AC cuts out (doesnt blow cold anymore) and the coolant runs out the overflow. Any ideas? Please help.