Upon arrival found system giving a error code 2 +3 which is for low pressure switch failed open. Checked flu pipe it was clear, checked exhaust and intake at rain cap and they were clear. This time the furnace would not lite the burners after resetting it. Called tech support and he had me check to see if board would lose 24v signal from pressure switches and it didn’t. Tech support said that since it never lost signal the control board is bad. Told tech support that previous company tried replacing board and it didn’t work. Previous company also had pressure tubes reversed when new board was installed. Board ordered at Lennox in Allen. Order#33781055