I have an American Standard heating and cooling unit. The fan in the attic runs 24/7. We have been told to disconnect the green wire in the thermosat to see if that was the problem we did that and it still ran. Then we were told that it could be a relay gone bad. When he opened the panel in the attic there was a lot of rust on the wires and the screws could this be causing our problem and several of the wires were touching each other. I do live in the great South were the humidity is always a problem can you help me?

Could be wires

Could be relay

Could be fan limit control.

Best to call a Heating and A/C contractor and get the ubit repaired. The average consumer can't fix these things.