Arrived to do a performance maintenance. Set up for combustion analysis temperature split and static pressure tests. Found that the system is putting out excessive heat and is operating with more static pressure than it is rated for. 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. Found that the fan for heating and cooling is heavily coated in dust debris. Checked systems heat exchanger to ensure proper venting of flue gas. Found that the furnaces secondary heat exchanger is impacted with dust debris and the primary heat exchanger is covered in hot spots from how hot the furnace is when operating. Found that the water heater vent does not have the proper pitch for good exhaust ventilation. Furnace is showing its age but is operational at this time.