Have lennox G20 Q4 furnace. Burners work when called for but no blower. Blower will not run when selected at thermostat. Had a new circuit board for the G20 Q3 furnace, installed it. Result was blower ran prior to burners igniting and blower would not go off after burner shut down. Changed thermostat batts.
I open for ideas.

Joe

Test all your fan and limit controls for proper operation. Recheck all of your connections on the new board.