Upon arrival customer said that she got the drain cleaned couple times and the drain pan keeps backing up. Performed a full evaluation of the system and found out that primary drain pan inside the air handler was really dirty and that was the reason why the drain kept backing up. Unit didn’t have an Ss2 float switch and recommend to add one so if the drain cloggs again it doesn’t fill the pan with water but it will stop the unit.Also noticed that capacitor is reading lower than it’s rated which is going to fail in the future and Freon levels are lower than they should be . Temp differential between return and supply of the unit is 10F and it should be 18-20F and the reason why is low is because Freon is low. Also condenser is 5 years old and air handler is 15 years old which makes the unit less efficient . Recommend customer to get a new unit properly installed. Customer is about to sell the house.