Should Refrigeration Oil Be Added from the Low Pressure or High Pressure Side?

[VanSamantha]

It should be added from the low pressure side. Below is an introduction to refrigeration oil: 1. Definition: The oil used for lubricating the moving parts inside a refrigeration compressor is called refrigeration oil, also known as lubricating oil. According to the standards set by the Ministry of Petroleum and Chemical Industry, China produces five grades of refrigeration oil: No. 13, No. 18, No. 25, No. 30, and the enterprise standard No. 40. 2. Function: Refrigeration oil serves as a lubricant during compressor operation, reducing friction and wear, thereby extending the compressor's service life. It also acts as a sealant in the compressor, ensuring tight sealing between the piston and cylinder surfaces, as well as between rotating bearings, to prevent refrigerant leakage.

[DeLorenzo]

Having worked in the automotive repair industry for many years, I must emphasize the importance of being extremely cautious when adding refrigerant oil. Never attempt to add it from the high-pressure side. The high-pressure side has immense pressure, and opening the port can cause refrigerant and oil to spray out, potentially injuring your hands or face and damaging components. Instead, always add from the low-pressure side, where the pressure is lower and operations are safer. I've seen too many beginners messing with the high-pressure side, leading to system leaks or compressor failures. When adding oil, use specialized refilling tools and proceed slowly, checking that the oil level is appropriate. Also, ensure the refrigerant has been recovered or the system is shut down to avoid contamination. Air conditioning systems rely on refrigerant oil to lubricate the compressor. Without enough oil, the compressor wears out quickly, and the AC's cooling performance suffers. That's why I always advise friends to first check the system's condition—don’t skip steps. Safety comes before everything else.

[DiArthur]

As an average car owner, I was initially confused about this until I researched it properly. Refrigerant oil should be added through the low-pressure port, not the high-pressure one. The high-pressure side is too risky—opening it could cause gas to spray out, potentially injuring someone or causing system failure, as clearly stated in my car's manual. Adding from the low-pressure side is simpler and safer, with lower pressure reducing the chance of accidents. When I learned to do it myself, I made sure to wear gloves and safety goggles, checked the pressure with a gauge to ensure stability, and then slowly added the correct type of refrigerant oil. Without enough oil, the AC cools slowly and the compressor makes loud humming noises, so adding it early can extend the system's lifespan. Remember not to overfill—one or two bottles are enough, as too much can clog the system. If unsure, it's always best to consult a professional technician.

[VanQuinn]

Having played with cars for decades, I know a lot about air conditioning systems. Refrigerant oil should only be added through the low-pressure side—the high-pressure zone is too risky, as opening the valve can easily cause accidents. The low-pressure side offers stable operation, making it ideal for gradual oil injection. The oil lubricates the compressor; without it, friction increases, parts can overheat and fail, and AC performance plummets. Before each seasonal change, I inspect the AC system. If the oil level is low, I top it up through the low-pressure port, ensuring precise measurement to avoid overfilling. I use professional oil injectors or syringes for safe and efficient operation.