Performed leak search on unit, started at evaporator coil and found that the back of the coil was leaking. I was unable to pinpoint the leak with my leak detector due to the amount of refrigerant floating inside of the unit. Customer is available on Tuesdays and Thursdays only for personal reasons. Unit was topped off with 7 lbs R410A due to the customer being 83 years old. System is operating properly at this time and date.