Tech arrived on site. Found 1 4 ton split system cooling. Oil was around the condenser. Client said it made a hissing sound when it shut off. Took apart the condenser and noticed the coils were dirty. Used a IR leak detector to check for refrigerant leaks. Found none. Checked charge. It was good. Documented it. Cleaned condenser coils. Leak client know to monitor the oil leakage to see if anything more happens. Unit is operational upon departure.