Arrived to do a performance maintenance. Set up for combustion analysis temperature split and static pressure tests. Verified operation of all mechanical and electronic components of the furnace. Checked blower for cleanliness and to see if there is any play in the bearings. Checked systems heat exchanger to ensure proper venting of flue gas. Performed an electronic gas leak search. Verified operation of the humidifier. Found that the humidifier panel is coated in calcium and bacterial growth. With homeowners approval replaced the humidifier panel and cleaned up the interior of the humidifier. Furnace and humidifier are operational at this time.