A/C Refrigerant Leak Detection
An oily spot on an A/C hose can indicate a refrigerant leak in the system. Proper oil levels are vital to system performance. If the level is too low, the compressor starves for lubrication. If the level is too high, heat exchange is affected, resulting in poor air conditioning performance. Replace the same amount of oil that was lost.
Refrigeration oil is mixed and distributed throughout the system in the refrigerant. If a leak has formed on an A/C hose, an oily spot that's collecting dirt appears. A refrigerant leak detector helps verify any suspicions and ensures that it's not another fluid splashed onto the hose. Some oils contain dye that is viewed with a black light and special yellow-tinted glasses. The dye can also be injected into a system with hard to find leaks to aid in visual diagnosis.
Always use the manufacturer's specifications and recommendations when adding oil to an automotive air conditioning system. Today's R134a systems use PAG (polyalkylene glycol) oil of different viscosities. PAG has replaced the mineral oil used in older R12 systems. This oil is hygroscopic; it absorbs moisture from the air. Keep the lid on the container when in storage.