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:
Fiber-Optic Cable, Assembling
Special tools and workshop equipment
required
Fiber-Optic Conductor Repair Set -VAS6223A-
Hose Cutting Pliers -VAS6228-
Vehicle Diagnostic Tester
It is very diffi ...
Catalytic converter
First read and observe the introductory information
and safety warningsThe catalytic converter is used for exhaust gas post-treatment
and helps to reduce exhaust emissions. To help ensure long-term functionality in
the exhaust system and the catalytic converter:
Use unleaded petrol only.
...
Cleaning wheels
First read and observe the introductory information
and safety warningsCleaning steel wheels
An industrial cleaner is needed to remove accumulated brake dust. Steel wheels
should therefore be cleaned regularly with a separate sponge.
Any damage to the paint on steel wheels should be touched u ...
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Refrigerant R134a Physical Data
Refrigerant R134a Environmental Information