Audi A4 2001 - Locking Mechanisms and Access Systems

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1.1.5 Refrigerant Oil
Caution
♦ Handling refrigerant oil, refer to Audi ServiceNet, HSO
Environment (or Volkswagen ServiceNet, Handbooks,
Service Handbook; Protecting the Environment, Emis‐
sions Protection).
Refrigerant oil mixes with the refrigerant (about 20-40%, depend‐
ing on compressor type and amount of refrigerant) and circulates
constantly in the system, lubricating the moving parts.
Special synthetic refrigerant oils, such as 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 con‐
ditioning system could be corroded as a result of mixture flowing
through the refrigerant circuit under pressure at high tempera‐
tures or breakdown of the lubricating film in the compressor. Using
non-approved oils can cause the HVAC system to malfunction.
Only use approved oils.
Refer to Electronic Parts Catalog (ETKA).
Type of oil for R134a in motor vehicles: PAG (polyalkylene glycol)
oil
Note
♦ Do not store open containers of refrigerant oil because it at‐
tracts moisture.
♦ Always keep oil containers sealed.
♦ Do not use old refrigerant oil over again. Disposing of refrig‐
erant oil of unknown origin, refer to Audi ServiceNet, HSO
Environment (or Volkswagen ServiceNet, Handbooks, Serv‐
ice Handbook; Protecting the Environment, Emissions Pro‐
tection).
♦ Ester-based oils are only intended for use in large systems,
not in passenger vehicle systems.
♦ Refrigerant Oil Characteristics, refer to
⇒ “1.1.6 Refrigerant Oil Characteristics“, page 7 .
1.1.6 Refrigerant Oil Characteristics
The most important properties are a high degree of solubility with
refrigerant, good lubricity, absence of acid and minimal water
content. Only certain oils are permitted. For a list of approved re‐
frigerant oils and capacities, refer to
⇒ “3.3 Refrigerant Oils“, page 117 .
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 aging of refrigerant oil,
causing it to become dark and viscous as well as corrosive to‐
wards metals.
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...
Refrigerant R134a Servicing - Edition 01.2011
1. General Information 7