Arrived to do a performance maintenance. Set up for combustion analysis temperature split and static pressure tests. Found that the system is operating with failing static pressure. 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. Found large hot spots and wear and tear but no damage. Performed an electronic gas leak search. Verified operation of the humidifier. Humidifier is in need of a solenoid valve. Verified operation of the heat pump upstairs. Checked unit for cleanliness. Verified operation of the heat strips. Furnace and air handler are operational at this time.