New Beetle L4-1.8L Turbo (BNU) (2005)
Refrigerant: Description and Operation
Refrigerant R134a
Refrigerant R134a
Vehicle air conditioning systems make use of the vaporization and condensation process. Use is made of a substance with a low boiling point, which is
called refrigerant.
The refrigerant employed is tetrafluoroethane R134a, which boils at -26.5 degree C at a vapor pressure of 1 bar.
Physical data of refrigerant R134a
Chemical formula
CH2FCF3 or CF3CH2F
Chemical designation
Tetrafluoroethane
Boiling point at 1 bar
-26.5 degree C
Solidification point
-101.6 degree C
Critical temperature
100.6 degree C
Critical pressure
40.56 bar (absolute)
Critical point
The critical point (critical temperature and critical pressure) is that above which there is no longer a boundary between liquid and gas.
A substance above its critical point is always in the gaseous state.
At temperatures below the critical point, all types of refrigerant in pressure vessels exhibit both a liquid and a gas phase, i.e. there is a layer of gas above
the liquid.
As long as both liquid and gas are present in the vessel, the pressure is governed by ambient temperature.
NOTE: Different types of refrigerant are never to be mixed. Only the refrigerant designated for the corresponding A/C system may be used.
Environmental aspects of refrigerant R134a
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R134a is a fluorocarbon and contains no chlorine.
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R134a has a shorter atmospheric lifespan than refrigerant R12.
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R134a does not deplete the ozone layer.
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The global warming effect of R134a is ten times less than that of refrigerant R12.