My air is working fine but my fan never shuts off. Is this the thromstat or something else that I need to call for a service call?

There is usually a switch on the thermostat labeled "Fan - Auto/On". Make sure it is set to Auto. If it is, I'd flip it to On and then back to Auto just to make sure. The only other thing I can think of is a short somewhere in the fan control circuit that is causing the fan to always run. Were there any recent changes to your system? These things generally don't just appear out of nowhere.

Best of luck,
WallyH

Fan relay is probably stuck