Blue shield fall service. Homeowner recently replaced filters, left 2 filters. Blower motor run capacitor checked good, motor and wheel are clean, inducer motor run capacitor checked good, hot surface ignitor checked good, cleaned and checked flame sensor, pressure switches (2) checked good, inducer motor run load amps are within mfg specs, all limits and safeties checked good, manifold is 3.5 in wc, within mfg specs, air temperature rise was 47 deg, within mfg specs. Carbon monoxide 0 ppm. System operating normally.