I just replaced the ignitor on this unit and after the flame is ignited the blower motor runs 24-7. If I shut off the ac to it and back on the motor does NOT come on. When it lights up again the motor stays on.. Steam heat 1 pipe

Weil-McClain?? Is this a boiler you have? If so the small powered fan motor for the exhaust should only run when there is a call for the boiler to fire to heat. Check other controls to be sure all else OK.