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. Found that the inducer is leaking condensation from the systems exhaust. Checked blower for cleanliness and to see if there is any play in the bearings. Found that the furnace fan is coated in dust debris. Checked systems heat exchanger to ensure proper venting of flue gas. Verified operation of the humidifier. Humidifier panel is coated in calcium buildup and is leaking. Furnace and humidifier are operational and humidifier is off at this time.