Performed scheduled furnace tune-up on 1983 model. System running but exhibiting short cycling after approximately 5 minutes due to limit switch activation. Diagnostics revealed severely plugged secondary heat exchanger, dirty blower wheel with worn bearings, and oversized blower motor capacitor (7.5μF rated, measuring 9.1μF). Recommended system evaluation by advisor before proceeding with necessary repairs including blower wheel cleaning, secondary heat exchanger cleaning, and blower motor replacement.
