Quote:
Originally Posted by SD1too
Workshop Manual (RAVE), Service Procedures, Air Conditioning, Condenser, Refit, 82-11:
"1. e. Lubricate new 'O' rings and threads of plug with clean refrigerant oil.
8. Lubricate new A/C pipe 'O' rings with clean refrigerant oil."
Simon
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Polyalkylene Glycol (PAG) oil
PAG oil is a man-made lubricant that is used in R134a and R-1234yf A/C systems, although the two types of PAG oil are different. There are several viscosities of PAG oil used by vehicle and compressor manufacturers and using the wrong viscosity oil in a compressor may create abnormal compressor noise and possible premature internal component wear.
By its chemical structure PAG oil is hygroscopic, meaning it attracts and retains moisture which can come from the atmosphere or from the A/C system. PAG oil and moisture together are not a good combination as when they mix, it forms an acid, causing damage or failure to system related components.
This type of oil should never be used to lubricate O-rings, compressor shaft seals or refrigerant line joints as in time corrosion can set in, which may cause a refrigerant leak. If the corrosion becomes severe enough, joints and fittings can fuse together and may not be removable during a future service repair.
There are some guidelines to follow when using PAG oil to keep it as moisture-free as possible:
When repairing an A/C system where refrigerant components are being removed, immediately seal off component fittings to minimise atmospheric moisture from entering a component or the system.
When installing replacement parts, keep caps on the part, except when you’re performing an oil balance or are ready to install the part. This too will minimise exposure of the PAG oil to atmospheric moisture.
The moisture absorption rate of PAG oil can occur at a rapid pace. If a container of PAG oil was left open overnight, it must not be used as it will have absorbed too much moisture to be effective in an A/C system.
To keep moisture to a minimum, always reseal the container immediately after dispensing PAG lubricant from it. If it is not known whether a container of PAG lubricant has not been properly resealed, do not use it.
Pull a vacuum on the refrigerant system after it has been repaired. Follow proper refrigerant recovery and recharging procedures, which typically includes a minimum vacuum of 45 minutes, to remove any moisture that has entered the A/C system during its repair.