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:
Warning lamp and coolant temperature display
Fig. 138 Coolant temperature display in
instrument cluster: Ⓐ cold; Ⓑ normal; Ⓒ warning
First read and observe the introductory information
and safety warningsA display for the coolant temperature may be, depending
on the vehicle equipment, located in instrument cluster. In normal driv ...
Additional Information Sources
Technical Service Handbook outlining action to be taken to
rectify current problems.
For the repair manual for model-specific repair work. Refer
to
→ Heating, Ventilation and Air Conditioning; Rep. Gr.87.
...
Midtronics Battery Tester -MCR340VKT-, Troubleshooting
Sometimes the display shows the malfunction or the messages
based on the condition.
The following is a list of the most frequent displayed
messages together with suggested solutions.
Note
Refer to the MCR3 ...
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Refrigerant R134a Physical Data
Refrigerant R134a Environmental Information