Bentley Volkswagen.Golf.Jetta.R32.Official.Factory.Repair.Manual.1999-2005

General information on refrigerant circuit
Página 19 de 21
pressure is modified on the low pressure side by the valve.
Tests and measurements performed using
pressure gauge
Indicators on pressure gauge
1. Temperature scale for refrigerant R134a CF3CH2F or
CH2FCF3.
2. Pressure scale
Pressure gauge may have one or more temperature scales
next to pressure scale. R134a scale values are allocated
respectively in the vapor pressure table. Since various
refrigerants create different vapor pressures at the same
temperature, each temperature scale is identified for the
respective refrigerant.
Pressure gauge makes the following tests and
measurements possible
a Pressure and temperature measurement at
refrigerant circuit
- High pressure gauge measures pressure and
temperature, which expand uniformly from outlet of A/C
compressor via the condenser up to constriction (restrictor,
or expansion valve) with A/C system switched on.
- Low pressure gauge measures pressure and
temperature, which expand uniformly from constriction
(restrictor, or expansion valve) via evaporator up to input of
A/C compressor with A/C system switched on.
Note:
- The relationship between pressure and temperature
indicated on the gauges only exists in a refrigerant circuit
containing liquid or vapor, but not gas. In gaseous state,
the temperature is approx. 10 C to 30 C higher than
indicated on the gauge.
b Verification of refrigerant in a closed vessel
Refrigerant R134a is present in a closed vessel or in a
refrigerant circuit when temperature indicator on gauge
matches the refrigerant temperature (standing liquid adopts
the ambient temperature).
A closed vessel or a refrigerant circuit which has been
switched off is empty when temperature indication on
http://ebahn.bentleypublishers.com/vw/servlet/Display?action=Next&type=repair&id=...
13/2/2005