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 will starve for lubrication and fail. If the level is too high, heat exchange is affected resulting in poor air conditioning performance. If a component has been replaced or if a leak has left the system low on oil, the same amount of oil that was lost must be replaced.
Refrigeration oil is mixed and distributed throughout the system in the refrigerant. If a leak has formed on a hose or at a connection, an oily spot will appear. This wet spot is likely collecting dirt and may be a refrigerant leak. A sniffer will verify any suspicions. Some oils contain dye that can be seen with a black light and special yellow tinted glasses. Dye can also be injected into a system with hard to find leaks to aid in visual diagnosis.
Always use 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.