Performed comprehensive maintenance on Goodman GSX16 air conditioning system. Cleaned condenser coils using Nu-Calgon Alka-Brite Plus. Checked refrigerant charge with Fieldpiece SMAN360 digital manifold, adding R-410A to manufacturer specifications. Inspected and tightened electrical connections. Replaced worn contactor with Supco SCP134. Lubricated fan motor bearings with CRC 03080 Power Lube. Cleaned evaporator coil with Nu-Calgon Evap Pow'r-C. Flushed condensate line using Rectorseal Drain Solve. Replaced air filter with Filtrete MPR 1900. System now operating at peak efficiency with 20°F delta T.