I conducted a comprehensive diagnostic on the Trane HVAC system, starting with a visual inspection of all components. I checked the thermostat settings, electrical connections, and refrigerant levels. I also tested the blower motor, capacitor, and control board for proper functionality. After identifying a faulty capacitor, I replaced it and recalibrated the system. Finally, I performed a thorough cleaning of the air filters and coils to ensure optimal performance. The system is now running efficiently.