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:
Flat Connector Systems
Note
If necessary, housing securing mechanisms (secondary locks)
must be released or removed using specified tool before
releasing the contacts. Refer to
→ Chapter „Secondary Lock“.
...
Product Characteristics
Refrigerants used in motor vehicle air conditioning systems
belong to the new generation of refrigerants based on
chlorine-free, partially fluorinated hydrocarbons (H-FKW,
R134a).
With regard to their physical properties, these are
...
Fitting the front towing eye
Fig. 193 In bumper at front right:
depiction of variants for screwing in towing eye
First read and observe the introductory
information and safety warnings
The towing eye is screwed into a threaded hole behind a cover on the right of
the front bumper .
The towing eye must always be kept i ...
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Refrigerant R134a Physical Data
Refrigerant R134a Environmental Information