Volkswagen Golf Service & Repair Manual: Refrigerant R134a
| Air conditioners in vehicles use the evaporation and
condensation process. The system contains a liquid with a low
boiling point, called the refrigerant. |
| The refrigerant used is tetrafluoroethane R134a, which boils
at -26.5°C with vapour pressure of 1 bar. |
|
| Physical data of refrigerant R134a |
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|
| Chemical formula |
CH2F–CF3 or CF3–CH2F |
| Chemical designation |
Tetrafluoroethane |
| Boiling point at 1 bar |
-26.5°C |
| Freezing point |
-101.6°C |
| Critical temperature |
100.6°C |
| Critical pressure |
40.56 bar (technical) pressure
equates to 39.5 bar (standard) pressure |
| Critical point (critical temperature and critical pressure)
means the point above which there is no longer a surface of
separation between liquid and gas. |
| Above its critical point, a substance is always gaseous. |
| At temperatures below the critical point, all types of
refrigerant contained within a pressure tank exhibit a liquid
phase and a gas phase, so that there is a gas cushion above the
liquid. |
| As long as there is gas in the pressure vessel alongside the
liquid, the pressure depends directly on the ambient temperature
→ Chapter. |
 Note
| Different types of refrigerants must not be mixed with each
other. Only refrigerants specified for the respective air
conditioning system may be used. |
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| Environmental aspects of refrigerant
R134a |
| R134a is a fluorocarbon and contains no chlorine. |
| R134a has a shorter atmospheric persistence than refrigerant
R12. |
| R134a does not damage the ozone layer, the potential to
reduce the amount of ozone is zero. |
| The Global Warming Potential (GWP) of R134a lies by
approx. 1430 (the GWP for carbon dioxide lies by 1). |
| The contribution of R134a to the greenhouse effect is less
by a factor of 10 than that of refrigerant R12. |
|
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The vapour pressure table for each refrigerant is published
in the literature for refrigeration engineers. This table shows
the vapour pressure exerted on the liquid ...
Other materials:
Programming the auxiliary heater
First read and observe the introductory information
and safety warnings Before programming, check that the date
and time set in the vehicle are correct .
The auxiliary heater can be programmed via the Auxiliary heater menu in the infotainment
system.
Opening the Auxiliary heater menu ...
Removing and installing radiator grille
Removing
Note
On vehicles with a flap for the charging bay in the radiator grille,
the connector must be disconnected first.
–
Remove bolts -2-.
–
Release catc ...
Blowing through refrigerant circuit with compressed air and nitrogen
Use compressed air to force moisture and other contaminants
out of the refrigerant circuit and use nitrogen to force
moisture out of the refrigerant circuit.
The method of blowing through the refrigerant circuit with
compressed air ...
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Vapour pressure table for refrigerant R134a