Performed comprehensive furnace tune-up on 30-year-old RPI II system with intermittent operation issues. Adjusted gas train pressure from 3.94 inWC to 3.34 inWC and cleared accumulated debris from condensate drain line and trap. Verified proper function of inducer motor, capacitor, pressure switch, control board connections, and thermostat operation with combustion CO recorded at 2 ppm. Noted moderate condition of return air filter; system now operating normally.
