Furnace operating upon arrival. Performed Furnace tune up. Media filter 16x25x4 like new. Opened bypass damper for humidifier at set to 35%.Performed combustion analysis found no traces of carbon monoxide in return air or supply air at this time. Cleaned flame sensor and vestibule area. HOT SURFACE ignitor reading 58ohms. GAS VALVE set at 1.7/3.5w/c. Amp draw on ecm blowermotorand inducer are within manufacturing specifications.System is operating normal and safe at this time