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 capacitor for the furnace fan is failing. Checked blower for cleanliness and to see if there is any play in the bearings. Furnace fan motor has worn bearings and the fan blades are heavily coated in dust debris. Checked systems heat exchanger to ensure proper venting of flue gas. Found that the evaporator coil is impacted with debris. Furnace is showing its age but is operational at this time.