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:
Retrofitting two-way radios
First read and observe the introductory information
and safety warningsYou will need an external aerial to use a two-way radio
in the vehicle.
Any retrofit installation of electrical or electronic equipment in the vehicle
will affect its vehicle type approval. Under certain circumstances, thi ...
Cleaning and caring for the dash panel, wooden trims and plastic parts
First read and observe the introductory information
and safety warnings
Moisten a clean, lint-free cloth with water and clean the parts.
Treat plastic parts inside and outside the vehicle and the dash panel
with a special solvent-free plastic cleaning and care product
that has been a ...
Legal Requirements
The manufacturer is granted general type approval for the
whole vehicle including all parts and for specific retrofitting
(general type approval according to § 20 StVZO (Motor Vehicle
Construction and Use Regulations or EU type approval).
...
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