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:
Indicator lamp in the vehicle key
Fig. 20 Indicator lamp in the vehicle
key
First read and observe the introductory information
and safety warnings
If a button on the vehicle key is pressed briefly, the indicator lamp (arrow)
flashes once. The lamp will flash several times if the button is pressed and held,
e.g. convenien ...
Correct sitting position
Fig. 35 There must be a distance Ⓐ of
at least 25 cm between the driver and the steering wheel.
Fig. 36 Correct seat belt routing and
head restraint adjustment
First read and observe the introductory information
and safety warnings
The following details the correct sitting positions for ...
Decorative Trims, Replacing, Bolted Decorative Trims
These disc wheels are equipped with replaceable decoration
elements. Note the following when installing.
–
Clean the thread in the disc wheel before screwing in the
new bolts.
...
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Refrigerant R134a Physical Data
Refrigerant R134a Environmental Information