Executed comprehensive maintenance on Lennox XC20 variable-speed air conditioning system. Cleaned condenser coils using Viper Microcoil Clean solution with low-pressure rinse. Verified refrigerant charge using Fieldpiece SMAN460 digital manifold, ensuring optimal subcooling. Inspected and calibrated Lennox iComfort S30 thermostat. Cleaned evaporator coil with Nu-Calgon Evap Pow'r-C foam cleaner. Flushed condensate line using Rectorseal Drain Solve and installed Rectorseal Clean Check valve. Replaced air filter with MERV 16 Lennox PureAir. Tested capacitor and contactor with Fluke 902 FC HVAC meter. Lubricated condenser fan motor with Super Lube 21030. System now operating at peak efficiency with 19°F delta T.