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:
Information stickers and plates
First read and observe the introductory information
and safety warningsSafety certificates, stickers and plates showing important
vehicle operation information are factory-fitted in the engine compartment and on
certain parts such as the tank flap, front passenger sun visor, the driver door
...
Important Information when Working with the A/C Service Station
Caution
If it is suspected that chemicals were added to the
refrigerant circuit to seal leaks, do not connect the
A/C service station and do not extract the refrigerant.
...
Driving in a fuel-efficient manner
Fig. 118 Fuel consumption in litres per
100 km at two different outside temperatures
First read and observe the introductory information
and safety warnings By adopting an economical driving style
and anticipating the traffic situation ahead, you can easily reduce fuel consumption
by 10- ...
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Refrigerant R134a Physical Data
Refrigerant R134a Environmental Information