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 System Operation
The temperature in the passenger compartment depends on the
amount of heat radiated through the windows and conducted by the
metal parts of the body. In hot weather it is possible to
achieve a more comfortable temperature for the passengers by
pumping of ...
A/C Compressor Regulator Valve -N280
Note
For switching pressures, removing and installing switches
and switch arrangement and version, see vehicle-specific
refrigerant circuit.
Refer to
→ Rep. Gr.87.
...
CAN Bus Wires, Repairing
Unshielded two-strand wiring -1-
and -2- with a cross section of
0.35 mm2 or 0.5 mm2
can be used as CAN bus wiring.
The color coding of CAN bus wires can be found in the
following table:
...
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Refrigerant R134a Physical Data
Refrigerant R134a Environmental Information