Performed a thorough annual maintenance service on a Trane 3-ton central air conditioning system for a residential client. The process began with a comprehensive inspection of the outdoor condenser unit, where I cleaned the coils using a foaming coil cleaner and a soft-bristle brush. I then checked the refrigerant charge, verifying the proper level of R-410A coolant using my manifold gauge set. Moving indoors, I accessed the air handler and replaced the disposable air filter with a new high-efficiency pleated model. I also inspected the evaporator coil, finding it in good condition, and ensured the condensate drain line was free of any blockages. Finally, I tested the thermostat and all electrical components to confirm the Trane system was operating at peak performance before completing the maintenance visit.