Upon arrival found system low on refrigerant. Indoor coils had begun to freeze as result of refrigerant loss. Performed leak check on coils without results. Found refrigerant oil around service valve and plastic caps that weren't sealing properly. Replaced with locking refrigerant caps accordingly. Recharged system to adequate levels. Returning next week to follow up and confirm whether system is holding refrigerant or continues to leak. Compressor has been strained due too loss of refrigerant and lack of lubrication when system was low on refrigerant. System is cooling properly at this time.