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. Found that the fan for heating and cooling is coated in dust debris. Checked systems heat exchanger to ensure proper venting of flue gas. Verified operation of the humidifier. Found that the humidifier is no longer receiving water. Barely got any water through the saddle valve and got absolutely no water through the solenoid valve. Spoke with homeowner about the system. With homeowners approval set up to clean the furnace fan and install a new humidifier with new valves as well as installing Uv to ensure the system stays free of bacterial growth. Furnace is operational at this time.