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:
Contaminants Removed from Refrigerant Circuit
The reservoir/receiver/dryer or dryer bag/cartridge should
not be replaced under the following conditions.
After an accident when there is no damage on the
reservoir/receiver/dryer.
The repair was done quickl ...
Improvised Tools
Note
This list outlines the testers, tools and materials required
for expert refrigerant circuit repair work.
Caution
Non-approved tools or materials such as leak sealing
additiv ...
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 ...
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Refrigerant R134a Physical Data
Refrigerant R134a Environmental Information