A common question here and you will find with a search there are many posts about the A/C fan running with the furnace.
Set the fan mode to AUTO on your thermostat to keep the A/C fan from running with the furnace.
Side note: Many folks actually like the A/C fan running... since heat rises... it distributes the heat more evenly.
2016 Flagstaff 8529IKBS Diamond Package 5th Wheel
Ford F-Series SCREW 4x4
TST Tire Monitor - Sinemate 3500w Gen.
2016 Nights Camped = 42