Friends and Family Fall furnace tune up in Comfort Maker 80% AFUE furnace. Homeowners have had no issues so far with running heat. Changed customer supplied filter, inspected and cleaned flame sensor. Checked blower, evaporator coil, train, hot water tank. Went in attic and shut damper doors underneath whirlybirds and lubricated whirlybirds as a courtesy. Cycled system on heating and checked order of operation. Checked gas pressure, replaced gas cap. Checked motor amps, heat rise. System is working great at this time!