Performed comprehensive AC maintenance on a Trane XR14 system. Inspected evaporator and condenser coils, cleaned with CoilShine-BC. Tested refrigerant charge using subcooling method, found slight undercharge. Added 8 oz of R-410A. Replaced clogged pleated air filter with MERV 11 media. Calibrated Honeywell T6 Pro thermostat and verified proper cycling. System now operating at peak efficiency.