Volkswagen Golf Service & Repair Manual: Refrigerant machine oil

Volkswagen Golf Service & Repair Manual / Air conditioning system with refrigerant R134a / General notes on air conditioning systems / Refrigerant machine oil

Refrigerant machine oil is miscible (approx. 20%–40% depending on the type of air conditioner compressor and the quantity of refrigerant) in the refrigerant. It circulates continuously in the circuit and lubricates the moving parts.

Special synthetic refrigerant machine oils such as polyalkylene glycol (PAG) oil are used in conjunction with R134a air conditioning systems. This is necessary because ordinary mineral oils are immiscible in R134a. In addition the materials of the R134a air conditioning system could be attacked if the mixture circulated within the refrigerant circuit under pressure and at high temperatures, or the lubricant film in the air conditioner compressor broke down. The use of unapproved oils can lead to the failure of the air conditioning system, so only approved oils must be used.

→ Parts catalogue

Type of oil for R134a in cars: PAG

Note

Do not store refrigerant machine oils open to the atmosphere since they are very hygroscopic (they readily absorb water).

Always keep oil containers tightly sealed.

Do not reuse used refrigerant machine oil.

Disposing of used oil: Volkswagen InfoNet; Operation; Manuals and dealership documentation; Service handbook; 15. Environmental Protection; Follow link “Environmental protection in the dealership and in the workshop” in "General notes"; 4. Waste disposal; 6. Disposal channels; g. Disposal of used oil; Refrigerant oils

Used refrigerant machine oils from systems with halogenated hydrocarbons (at least one hydrogen atom has been replaced by e.g the halogens flourine, chlorine, bromine or iodine) must be disposed of as waste requiring particular care. A mixture with other oils or materials is not permissible. Proper storage and disposal must be performed according to guidelines in the country where the work is being performed. Observe, for example in the Federal Republic of Germany, the climate protective regulation concerning chemicals; closed substance cycle waste management and ensuring environmentally compatible waste disposal (in other countries other statutes and regulations may apply)

Reference sources for technical rules and safety at work / accident prevention for the Federal Republic of Germany

Sources in other countries may be obtained from the responsible authorities.

Ester-based oils are suitable only for larger systems (not for air conditioning systems in cars).

Properties of refrigerant oils

The most important properties are high solubility in refrigerants, good lubrication characteristics, freedom from acid and very low water content. For this reason, only certain oils may be used. A list of approved refrigerant oils and quantities can be found in the vehicle-specific workshop manuals in → Rep. gr.00 or → Rep. gr.87.

The PAG oils suitable for refrigerant R134a are strongly hygroscopic and are immiscible with other oils. Therefore, opened containers should be closed again immediately to protect them from moisture. Refrigerant oils age under the influence of moisture and acids; they become dark, viscous and aggressive towards metals.

Note

For refrigerant circuits with refrigerant R134a, use only the oil approved for the air conditioner compressor. See → Rep. gr.00 or → Rep. gr.87 in the repair manual for the specific vehicle.

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