Completed AC repair on a Daikin DX20VC unit in Montclair, NJ. Diagnosed the problem as a refrigerant leak in the evaporator coil and a malfunctioning expansion valve. Repaired the leak and replaced the expansion valve to ensure proper refrigerant flow. Recharged the system with R-410A refrigerant, ensuring optimal levels. Cleaned the evaporator and condenser coils to enhance efficiency. Checked and adjusted system pressures for accurate superheat and subcooling values. Secured all electrical connections and tested the thermostat for precise temperature control. The unit is now operating efficiently, providing consistent and reliable cooling for the homeowner.