Preventative maintenence inspection on 2004 Trane furnace. System is operational but in poor condition. Clean flame sensor and check ignitor. Visual inspection of burners. Flush condensation trap. Humidifier pad in good condition, damper opened, run test during heating mode, set to 35%. 3" pvc flue in good condition and no sign of leaks. 0PPM CO detected during testing. Ran test in heating mode from Google Nest thermostat. Delta t of 41F with supply temp of 116F, delta t spec of 30-60F. Blower motor and blower capacitor are operating within spec. Inducer/exhaust motor is operating within Amp draw specifications, but has signs of water damage with rust on outer casing and parts internally on the motor. The exhaust motor/housing is also making a noise that sounds like bearing noise meaning the motor could fail soon. With the age and condition of the unit, in the event of a break down and a major part needing to be replaced, recommend replacing entire unit as it could become a money pit.