Volkswagen Polo Service & Repair Manual: Critical Point
| Vehicle air conditioning systems make use of the
vaporization and condensation process. In this case, one works
with a substance which boils easily, designated as refrigerant. |
| The refrigerant employed is tetrafluoroethane R134a, which
boils at -26.5 °C (-15.7 °F) at a vapor pressure of 1 bar (14.5
psi). |
| 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 there is still gas present in the container next
to the fluid, pressure is dependent on ambient temperature.
Refer to
→ Chapter „Refrigerant R134a Vapor Pressure Table“. |
 Note
| Different types of refrigerant are never to be mixed. Only
the refrigerant designated for the corresponding A/C system may
be used. |
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Vehicle air conditioning systems make use of the
vaporization and condensation process. In this case, one works
with a substance which boils easily, designated as ref ...
Vehicle air conditioning systems make use of the
vaporization and condensation process. In this case, one works
with a substance which boils easily, designated as ref ...
Other materials:
Handling wheels and tyres
Fig. 145 Diagram showing how to swap wheels
First read and observe the introductory information
and safety warningsThe tyres are the most used and most underestimated parts
of a vehicle. Tyres are very important as the narrow tyre surfaces are the only
contact between the vehicle and the ro ...
Gear-change indicator
First read and observe the introductory information
and safety warnings In some vehicles, the instrument cluster
will show which gear should be selected while the vehicle is in motion to reduce
fuel consumption.
Display
Meaning
The c ...
General Information
Battery Charger -VAS5906-
WARNING
Risk of injury. Follow all Warnings and Safety
Precautions. Refer to
→ Chapter „Warnings and Safety Precautions“.
...
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Refrigerant R134a Physical Data
Refrigerant R134a Environmental Information