Arrived to on site, unit was running but not cooling sufficiently. Measured pressures on the unit and found it to be low on refrigerant. Upon conducting a leak test I found a leak in the evaporator coil. Discussed with homeowners that the coil would need to be replaced in order to stop the leak. The unit is under parts and labor warranty, therefore the only things that would not be covered is the filter dryer and the refrigerant. As a courtesy, I added 2 Lbs. 13.5 Oz. Of refrigerant in order to provide some cooling as I was not able to provide an estimated timeframe for the repair. Unit was still low, but cooling better than it was. Informed customer that we would contact them tomorrow with more information on part availability and estimated time of repair.