Refrigerant Oil

Refrigerant Oil

Refrigerant oil mixes with the refrigerant (about 20-40%, depending on compressor type and amount of refrigerant) and circulates constantly in the system, lubricating the moving parts.

Special synthetic refrigerant oils, e.g. polyalkylene glycol (PAG) oil, are used in conjunction with R134a air conditioning systems. This is necessary as mineral oil, for example, does not mix with R134a. In addition, the materials of the R134a air conditioning system could be corroded as a result of mixture flowing through the refrigerant circuit under pressure at high temperatures or breakdown of the lubricating film in the compressor. The use of non-approved oils can lead to the failure of the air conditioning system and exclusive use is therefore to be made of authorized oils.

Type of oil for R134a in motor vehicles: PAG

NOTE:
- Do not store refrigerant oils in open containers as they are extremely hygroscopic (water-absorbing).
- Always keep oil containers sealed.
- Do not re-use old refrigerant oil. Dispose as old oil of unknown origin, refer to Customer service distributor/ServiceNet; handbooks; HSO; Volume 2; emission protection; refrigerant from A/C system / refrigerant oil). Ester-based oils are only intended for use with large systems (not for motor vehicle air conditioners).

Characteristics of refrigerant oil
The most important properties are a high degree of solubility with refrigerant, good lubricity, absence of acid and minimal water content. It is therefore only permissible to use certain specified oils. For list of approved refrigerant oils and capacities.

PAG oils, which are appropriate for refrigerant R134a, are highly hygroscopic and do not mix with other oils. Opened containers should therefore be closed again immediately to prevent ingress of moisture. Moisture and acids promote ageing of refrigerant oil, causing it to become dark and viscous as well as corrosive towards metals.

NOTE:
- For refrigerant circuits with refrigerant R134a, only approved oil may be used for the air conditioning compressor.
- Refrigerant oil, because of its chemical properties, must not be disposed of with engine oils or transmission oils. Dispose as old oil of unknown origin, refer to Customer service distributor/ServiceNet; handbooks; HSO; Volume 2; emission protection; refrigerant from A/C system / refrigerant oil).