Preventative maintenence inspection on high efficiency Carrier furnace running in great condition. 20x25x4 air filter in decent condition. Filter is currently in backwards. Make sure to insert filter in correct direction on next filter change. Clean flame sensor and check ignitor. Visual inspection of burners. Flush condensation trap and drain lines. Run test unit in heating mode from thermostat. Temperature rise is within specs. Blower and inducer motors tested good. Pvc flue vents in good condition and no sign of leaks. 0PPM CO detected during testing. System is operating properly, efficiently and ready for Winter.