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:
Checklist
Carry out the steps in the specified order :
With the engine at operating temperature,
park the vehicle on a level surface to ensure that the engine oil reading is
correct.
Switch off the engine and wait a few minutes
for the engine oil to flow back into the sump.
Open the ...
Stowage compartments in the front centre console
Fig. 94 In the centre console: stowage
compartment at the front
Fig. 95 In the centre console: stowage
compartment next to the handbrake lever
First read and observe the introductory information
and safety warnings
There is an open stowage compartment with lighting in the front centre con ...
High Pressure Sensor -G65
Note
For switching pressures, removing and installing switches
and switch arrangement and version, see vehicle-specific
refrigerant circuit.
Refer to
→ Rep. Gr.87.
...
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Refrigerant R134a Physical Data
Refrigerant R134a Environmental Information