Volkswagen Polo Service & Repair Manual: Commercial Names and Designations
Refrigerant R134a is currently available under the following
trade names: |
Note
Different trade names may be used in other countries. |
Of the wide range of refrigerants available, this is the
only one which may be used for vehicles. The designations Frigen
and Freon are trade names. They also apply to refrigerants which
may not be used in automotive vehicles. |
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Like water, refrigerants are colorless in both vapor and liquid form. Gas is
invisible. Only the boundary layer between gas and liquid is visible. (Liquid
level in tube of charging cylinder or bubbles in sight glass). Refrigerant R134a
fluid may appear colored (milky) in a sight glass. This cloudiness is caused by
partially dissolved refrigerant oil and does not indicate a malfunction.
In a partially filled, closed vessel, the quantity of
refrigerant evaporating from the surface equals the quantity
returning to the liquid state as vapor particles condense. This
state of equilibrium occurs under the influence of pressure and
is often called vapor pressure. Vapor pressure is dependent on
temperature. Refer to
→ Chapter „Refrigerant R134a Vapor Pressure Table“. |
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R134a Physical Characteristics
The vapor pressure curves of R134a and other refrigerants
are sometimes very similar, therefore it is not possible to make
a certain distinction solely by pressure. |
With R134a, the A/C compressor is lubricated with special
synthetic refrigerant oils, for example. PAG oils (polyalkylene
glycol oils). |
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Affect on Metal
In its pure state, refrigerant R134a is chemically stable
and does not corrode iron or aluminum. |
Refrigerant impurities such as chlorine compounds however
cause corrosion of certain metals and plastics. This can lead to
blockage, leaks or deposits on the A/C compressor piston. |
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Critical Temperature/Pressure |
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The refrigerant R134a remains chemically stable up to a gas
pressure of 39.5 bar (572.9 psi) (corresponding to a temperature
of 101 °C (213 °F). Above this temperature, the refrigerant
decomposes. Refer to
→ Chapter „Combustibility“. |
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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 ...
Other materials:
Start/stop system
Fig. 119 In the upper part of the centre
console: button for the start/stop system
First read and observe the introductory information
and safety warnings If the start/stop system is activated, the
engine will be switched off automatically when the vehicle is stationary. When required,
t ...
Tire Wear, Center
This wear pattern is found on drive wheels on high-powered
vehicles that often drive long stretches at high speed.
At high speeds, the centrifugal force increases the tire
diameter at the center of the tread more than at the shoulders
of ...
Oxygen Sensor Unit Protective Pipes
Note
In addition to using the part number, the protective pipe
can also be used for identification.
Version D1, 6 openings, 3.5 mm each
Only used with the 4-pin oxygen sen ...
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