Found unit not coming on, checked system and determined that it is either the main control board for the furnace or the blower motor. Control board is cutting in and out, need to replace control board before further diagnosis can be done. Found unit with the control board working intermittently and a weak capacitor on the blower motor, need to replace control board and capacitor before further diagnosis can be done. Net 15 Terms for Payment. Three Pole Contactors (2)