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:
Introduction
This chapter contains information on the following subjects:
→ Vehicle key
→ Indicator lamp in the vehicle key
→ Replacing the battery
→ Synchronising the vehicle key
Additional information and warnings:
Settings in the Volkswagen information system
...
Warranty Test, Performing
WARNING
Do not check or charge batteries that have a visual
indicator that is bright yellow. Jump starting must not
be used!
There is a risk of explosion during testing,
cha ...
Vehicle Electrical System, General Repair Information
Caution
Follow the procedure in the repair manual when
disconnecting and connecting the battery.
WARNING
Some tools are supplied wit ...
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Refrigerant R134a Physical Data
Refrigerant R134a Environmental Information