Arrived to do a performance maintenance. Upon arrival homeowner asked about the bacterial growth in the drain for the humidifier and drain for the air conditioner. Set up for combustion analysis temperature split and static pressure tests. Found that the system is operating with failing static pressure but is maintaining a great temperature split. 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 furnace fan is coated in dust debris. Checked systems heat exchanger to ensure proper venting of flue gas. Verified operation of the humidifier. Found that the solenoid valve is not allowing water to flow properly. Found that the solenoid valve is being fed by a saddle valve. Saddle valves are prone to being clogged or leaking. Spoke with homeowner about recommendations. Furnace and humidifier are operational at this time.