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Air conditioning systems with refrigerant R1234yf - General information - Edition 07.2017
Note
♦ Different trade names may be used in other countries.
♦ Of the wide range of refrigerants available, this is the only one
which may be used for vehicles. The names Frigen and Freon
are trade names. These also apply to refrigerants which are
not to be used in vehicles.
6.2.7
Colour and odour of R1234yf refrigerant
♦ Like water, refrigerants are colourless in both vapour and liq‐
uid form. Gas is invisible. Only the boundary layer between
gas and liquid is visible (liquid level in indicator tube of charg‐
ing cylinder or bubbles in sight glass). Liquid refrigerant
R1234yf may have a coloured (milky) appearance in a sight
glass. This cloudiness is caused by partially dissolved refrig‐
erant oil and does not indicate a fault.
♦ Refrigerant is almost odourless. Should R1234yf refrigerant
escape, it may be possible to detect a slight smell of ether
depending on the ambient conditions.
6.2.8
Vapour pressure of R1234yf refrigerant
In an enclosed container that is not completely full, refrigerant
evaporates at the surface in a quantity sufficient to form an equi‐
librium between vapour and liquid. This state of equilibrium occurs
under the influence of pressure and is often called vapour pres‐
sure. The vapour pressure is temperature-dependant
⇒ “6.1.3 Vapour pressure table for refrigerant”, page 17 .
6.2.9
Physical properties of R1234yf refriger‐
ant
♦ The vapour pressure curves of the two refrigerants, R1234yf
and R134a, are very similar across a broad temperature
range, which is why no difference can be established between
them
⇒ “6.1.3 Vapour pressure table for refrigerant”, page 17 and
⇒ Air conditioning system with R134a refrigerant, General in‐
formation about the air conditioning system . It is only possible
to determine a difference using relevant sensors, which can
analyse the chemical structure of the refrigerant
⇒ “6.2.16 Analysis of refrigerant R1234yf”, page 24 .
♦ Lubrication of the air conditioner compressor with R1234yf is
by special synthetic refrigerant oils, e.g. PAG oils (polyalky‐
lene glycol oils) with certain additives adapted to the R1234yf
refrigerant oil, the air conditioner compressor and the operat‐
ing conditions.
6.2.10
How R1234yf refrigerant reacts to met‐
als and plastics
♦ In its pure state, R1234yf refrigerant is chemically stable and
has no corrosive effect on e.g. iron, aluminium and specially
developed plastics that are suitable for this purpose.
♦ Contaminants in the refrigerant, however, cause components
of the refrigerant circuit to become corroded and damaged
beyond repair.
♦ Unsuitable materials (e.g. seals and hoses that were not de‐
veloped for the R1234yf refrigerant and the associated refrig‐
erant oil) can also be corroded and damaged by pure R1234yf
refrigerant and refrigerant oil.
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Rep. gr.00 - Technical data
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