Preventative maintenence inspection on Carrier high efficiency gas furnace. 20x25x1 air filter in new condition. Clean flame sensor and check ignitor ohms. 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.