Volkswagen Golf / Golf GTI / Jetta. Manual — part 1003

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

General information on refrigerant circuit

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gauge is below the temperature of the refrigerant.

Note:

- The relationship between pressure and temperature
indicated on the gauges no longer applies if no liquid is
present and the pressure is built up solely by gas.

Service and recycling units

At this time, service units for extracting, cleaning and filling
refrigerant for motor vehicle A/C systems are available on
the market from various manufacturers.

Classification of extraction systems in groups

Group 3:

Mobile extraction and charging systems for filling
compressed-gas vessels permanently connected to the
system.

The refrigerant or refrigerant/oil mixture is transferred to
compressed gas vessels which are permanently connected
to the mobile systems. In accordance with 3 Para. 5 No. 3
of pressure vessel regulations, compressed-gas vessels
are classified as pressure vessels in this case.

The charging systems require:

- no permit

- Do not require expert testing, as the gas is transferred to
compressed- gas vessels which are classed as being
pressure vessels (systems used for transfer from these
pressure vessels to compressed gas vessels for supplying
to third parties do however require a permit and are subject
to mandatory testing)

Note:

- The service and recycling units used in motor vehicle
workshops are extraction and charging systems not
requiring a permit (Group 3) but which are only to be
operated by qualified personnel. Instructions for unit
operation and maintenance can be found in the relevant
manufacturers documentation.

Charging systems not requiring a permit

Charging systems not requiring a permit are ones used for
transferring compressed gases to mobile compressed-gas
vessels for internal use only.

General information on refrigerant circuit

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Note:

Some service units are charging systems not requiring a
permit. When working with such equipment, the refrigerant
is not transferred to mobile compressed-gas vessels, but
rather into a permanently installed charging cylinder with
visible level gauge and float switch.

Recommendation:

It is advisable to use a portable cylinder with visible level
gauge and pressure relief valve for surplus refrigerant for
internal use.

Attention must be paid to TRG 402 (technical regulations
for compressed gases) when transferring compressed
gases to other compressed-gas vessels.

Refrigerant circuit repair information

Warning!

When performing work on refrigerant circuit, observe
all generally applicable safety precautions and
pressure vessel regulations.

Special tools and accessories:

The performance of proper workmanlike repairs on an air
conditioning system:

- Requires the use of special tools and materials as listed in

00-9, Testing equipment and tools

.

- Requires compliance with the basic instructions for use of
leak detectors

00-4, Refrigerant circuit, tracing leaks

using leak detector V.A.G 1796

.

- Requires expert knowledge.

Note:

- Environmentally hazardous draining of refrigerant is an
offense punishable by law

00-3, Laws and regulations

.

General information on refrigerant circuit

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00 - 3

Laws and regulations

Note:

- The laws and regulations listed below are applicable in
Germany. Different or additional laws and regulations may
apply in other countries.

Laws and regulations

8 Operation, maintenance, shutdown, obligation to
accept return

(1) With regard to operation, repair and shutdown of items
containing refrigerants as defined in 33, it is prohibited to
contravene the state of the art by allowing the substances
they contain to escape into the atmosphere.

A record must be kept of the quantities used during
operation and maintenance (refrigerant log, refer to
Environmental Protection Vol. 2-2. 43.2) and presented to
the relevant authorities on request.

(2) Distributors of the substances and preparations listed in
1 Para.1 and 2 are obliged to accept the return of such
substances and preparations after use or to appoint a third
party to accept return of these.

(3) The maintenance and shutdown of items containing
refrigerants as defined in 3, as well as acceptance of return
of the substances and preparations listed in 1 Para.1 and 2
may only be undertaken by persons with the necessary
expert knowledge and technical equipment.

9 Criminal offenses and infringements of the law

(3) An infringement of the law in terms of 26 Para. 1 No. 7
of the Law on Chemicals is constituted by willful or
negligent contravention of 8 Para. 1 Clause 1 during
operation, maintenance or shutdown of items containing
refrigerants as defined in 3 by allowing substances
contained in these to escape into the atmosphere contrary
to the state of the art, or by willful or negligent
contravention of the obligation to keep records as defined
by 8 Para. 1 Clause 2.

TRG (technical regulations for compressed gases) 400,
401, 402

Only excerpts concerning vehicle manufacturers and
workshops are listed below.

TRG 400 (general regulations for charging systems)

Laws and regulations

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