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:
Types of Batteries
General Information
Caution
The following batteries described are
maintenance-free batteries. Do not remove any of the
labels on the battery and do not add distilled water.
Only perfo ...
Introduction
This chapter contains information on the following subjects:
→ Washing the vehicle
→ Washing the vehicle with a high-pressure cleaner
→ Cleaning windows and exterior mirrors
→ Cleaning and changing windscreen wiper blades
→ Waxing and polishing the ve ...
Introduction
This chapter contains information on the following subjects:
→ An economic driving style
→ Driving in a fuel-efficient manner
Fuel consumption, environmental impact and wear on the engine, brakes and tyres
depend largely on three factors:
Personal driving style.
...
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Refrigerant R134a Physical Data
Refrigerant R134a Environmental Information