Ac clean and tune. Customer is stating that ac condenser froze up after tech was here last time to change filter and cleaned condenser. I cleaned electrical compartment. Used coil cleaner on condenser coil. Hooked up gauges and checked pressures and temps. Subcooling was a little high and indoor coil temp was at 30 degrees. Added 9 oz of R410-A refrigerant. Coil temp went to 38. Indoor split was 18. System operating normal at this time. Customer will watch system to see if added refrigerant made a difference in outdoor freeze up over nighttime hours. Office will follow up. Job complete.