Furnace clean and tune. Cycled system. Checked heat exchanger, ok. Checked, removed, and cleaned burners and flame sensor. Both ok. Igniter tested ok. Checked and adjusted gas pressures to maximize efficiency. Checked and tightened electrical connections and clamps. Cleared drain lines. Preformed combustion test and found normal levels in exhaust. No CO found in airstream. Checked humidifier and found no water running to unit. Cleared saddle valve. Water running to unit now. System operating normal at this time. Job complete.