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

13/2/2005

 

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

13/2/2005

 

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

13/2/2005

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

13/2/2005