The 3 1/2 ton unit was low on charge. I did a look over the system and did not see any oily residue. The homeowner move forward with the leak search. I disassembled the unit and went over it with a leak detector and did not register any other leaks other than the service valves failing leaking Freon. I replace the service valves and charge the system back to factory specifications. I cleaned both outdoor coils. The unit is operating properly at this time.