The fan on my Carrier runs non-stop. The burner kicks on from time-to-time, but the fan is a constant. It never did this until a few weeks ago (settings didn't change). I put new batteries in the thermostat to see if that would help - it didn't. Any ideas to get the fan to shut off?

Make sure the fan is set to auto and not on

The fan is set to auto.

Post model # of unit if possible, look for a diagnostic LED behind a clear plug, if present and blinking observe pattern, then consult service label for translation.