What’s Harmful to A/C System Lubricant?

What’s Harmful to A/C System Lubricant?


The correct type and right amount of oil is vital for the compressor's health & performance. The air-conditioning compressor is no different to a car engine, it needs the appropriate type and amount of oil to operate properly. A thin coating of oil between the compressor pistons and the cylinders ensures smooth operation and proper refrigerant sealing. The oil not only lubricates the compressor, but also acts as a cooling agent, absorbing heat from the compressor and preventing it from over-heating. The oil also prevents o-rings and seals in the system from drying out and perishing.


Compressor manufacturers specify the oil that should be used with their compressors and original equipment manufacturers will test the oil in any warranty claim to ensure that the correct oil has been used.



Using additives is not wrong, but using them incorrectly can and will harm the compressor and compressor oil. If you use too much additive or an additive that is incompatible with the oil, the oil properties will change and the effectiveness of the oil to lubricate will diminish.


When the original oil is mixed with another substance, it can and will affect the structure and composition of the oil film and thereby weaken its lubricity. This will affect the performance of the compressor and ultimately shorten its lifespan. If the oil does not meet the specifications of the compressor, this will lead to the compressor overheating, excess friction of the internal components of the compressor and ultimately compressor seizure.


It is vital that you adhere to the manufacturer's instructions and ensure that the correct oil is used when fitting a compressor. Always use the oil that the manufacturer has suggested, as well as the correct volume of oil.


When you add UV dye or leak stop, make sure that you follow the instructions to ensure you add the correct amount and that it is compatible with the oil being used.


- Using too much dye in the system will dilute the oil, especially if the dye is detergent based. The result will be the viscosity of the oil changing, resulting in poor lubrication and the compressor failing. Adding too much oil-based dye would increase pressure within the system thereby putting extra pressure on the compressor. The amount of dye added to the system should never be more than 5% of the total volume of oil in the system.

- Improper evacuation will leave moisture in the system. Some leak stops work by crystalizing moisture in leakage areas; a badly vacuumed system will experience extensive crystallisation. This will cause contamination inside the system, reduce the effectiveness of the oil and will lead to compressor failure and drier failure.

- Flushing the system is great, but if the system isn't dried correctly afterwards, the fluid will impair the abilities of the oil and destroy the Teflon coating of the compressor internals.


AP Air Europe Ltd is a leading supplier of air conditioning parts for agricultural and construction vehicles, delivering to 52 different countries. Search over 50,000 products by vehicle or part/OEM number and read more informative blogs at www.apairltd.com

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