I never use my central air. it is set to off. fan has on or auto setting. It has always been set to auto, and does not go on, which is the way i want it. the other day, the fan started going on and off...and will not stop. no matter where i have the thermostat set..it keeps going on and off. what's up with that? thanx in advance for your time!
Could be any number of things, from a faulty board, to a faulty wire, faulty limit, faulty tstat ... the list goes on for a bit.
You can eliminate certain things pretty easily - for example, remove the G wire from the tstat wiring terminals. If the fan issue stops, then most likely the tstat is bad. If it continues, the stat is not your trouble.