Performed preventative maintenance on a Ruud furnace. Upon arrival I performed a combustion analysis test and the O2 is 7% and CO is 5 ppm. I checked all electrical connections to ensure they are secured. Checked pressure switch tube for clogs. Cleaned flame sensor and burner box. Homeowner says unit was a little louder than last year, sound coming from inducer motor but does not seem to have an issue, pulled correct amps, windings are in good condition. Changed filter sized 16x25x1. Returned thermostat to homeowner setting. Unit is operating properly at this time. Model # UGPN-07EAMER Serial # FU5D302F170801052 Filter 16x25x1