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:
A/C Programmer -J127
This programmer switches the refrigerant flow direction
through the second evaporator if the temperature on the cooling
fins on the second evaporator lowers to the freezing point for
water (icing protection).
...
Emergency Wheels
Spare Wheel Notes
If Necessary, Explain to the Customer the Information About
Tires and Refer the Customer to the Owner's Manual.
The following notes listed also apply to spare wheels that
are marked wi ...
Wheel bolt caps
Fig. 165 Removing the wheel bolt
caps
First read and observe the introductory
information and safety warnings
Take the wire hook from the vehicle toolkit .
Insert the hook through the opening in the cap and pull off in the
direction of the arrow.
The caps protect the wheel b ...
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