Oil...The Lifeblood of the A/C System
The correct type and amount of oil is important for the performance of the A/C system. Always refer to the manufacturer specifications, typically located on the under-hood decal, regarding oil and refrigerant charge.
Oil is the lifeblood of the A/C system for several critical reasons:
- LUBRICATION: The A/C compressor relies on oil for lubrication to reduce friction and prevent metal-to-metal contact. Proper lubrication reduces premature failure, excess wear and tear and prevents damage due to contaminated oil in other parts of the A/C system.
- LUBRICATIONHEAT EXCHANGE: The oil in the A/C system also helps to dissipate heat generated in the compressor as it pressurizes refrigerant.
- SEAL PRESERVATION: To maintain the integrity of seals and O-rings in the A/C system, it is important they remain lubricated to prevent premature breakdown that can lead to leaks in the A/C system.
It is best practice to drain the oil from a failed compressor. Oil from a failed compressor can provide valuable information about the cause of failure. If there is significantly less oil drained from the compressor than what should have been in the system, this indicates a leak.
If the oil is a dark color and/or with metal particles, this indicates internal damage such as bearing or piston failure. Low oil levels, whether an undercharged compressor or leak in the system, can increase friction and wear on internal components, resulting in metal particles as well. |
A red oil color indicates the presence of moisture in the oil can indicate the system was exposed to the atmosphere, whether during improper service or a leak, potentially causing corrosion and subsequent failure. |
In a well-functioning system, compressor oil will look yellow. Compressor oil with dye will have a green color. |
Please note:
- Hybrid/Electric systems replace Polyol Ester (POE) oil, a non-conductive oil with high dielectric properties. Using PAG oil can break down the insulating properties of windings on the electric motors. Refer to gpd Tech Tip #79 for more information.
- The oil drain plugs on the Denso 7SBH17C, V5, V7, Sanden, and 7SEU style compressors must be removed to drain oil. Completely draining the oil will take a fair amount of time due to compressor styler. Refer to gpd Tech Tip #38 and gpd Tech Tip #121 for more information.
- Some late model compressors are designed with an oil separator and may feature a low oil capacity. This design may also require a fair amount of time to properly drain.
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| gpd_tech_tip_4-compressor-oil-automotive_air_conditioning.pdf |
