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:
Extraction System Group Classifications
At this time, A/C service units for extracting, cleaning and
filling refrigerant for motor vehicle A/C systems are available
from various manufacturers.
Group 3:
Mobile extraction and charging systems for filling
c ...
AGM Battery
Maintenance-Free Battery with Specific Electrolyte without a
Visual Indicator
Lead-acid battery, where the electrolyte is fixed in an
absorbent glass mat (AGM). The battery is closed and equipped
with breather valves.
...
Water Content
Only very small amounts of water are soluble in liquid
refrigerant. On the other hand, refrigerant vapor and water
vapor mix in any ratio.
Only a small drop of water may get into the refrigerant
circuit. The dryer, dryer bag or dryer car ...
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