Upon arrival system was not cooling efficiently I checked the pressures and system was low on Freon. Since this has been an on going issue with the system i recommended customer to add dye sealant. I added dye and .5 of 410a down the system. I informed customer if she has issue again when we come back it will be a quick leak search when we look for the dye. No charge for today because this is a callback and on going issue with the system.