Skoda 2012 Citigo Instruction manual

Workshop Manual
Citigo 2012 ➤ , Fabia 2000 ➤ ,
Fabia II 2007 ➤ , Fabia II 2009 ➤ ,
Fabia II 2011 ➤ , Fabia III 2015 ➤ ,
Octavia 1997 ➤ , Octavia II 2004 ➤ ,
Octavia II 2010 ➤ , Octavia III 2013 ➤ ,
Octavia III 2014 ➤ , Rapid 2011 ➤ ,
Rapid NH 2013 ➤ , Roomster 2006 ➤ ,
Superb 2002 ➤ , Superb II 2008 ➤ ,
Yeti 2010 ➤ , Yeti 2011 ➤
Air conditioning system with refrigerant R134a
Edition 10.2014
Service
Service Department. Technical Information
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List of Workshop Manual Repair GroupsList of Workshop Manual
Repair GroupsList of Workshop Manual Repair Groups
Repair Group
00 - Technical data
Service
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Contents
00 - Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1 General notes on the air conditioning system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Important instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Further documentation and information means . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Principles of the air-conditioning technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4 Advantages of the air conditioning system - comfort . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.5 Operation of the air conditioning system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.6 Refrigerant R134a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.7 Vapour pressure table for refrigerant R134a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.8 Properties of refrigerant R134a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.9 Evidence of leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.10 Refrigerant oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.11 General occupational safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.12 Using pressure tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.13 Safety precautions when working with extraction and filling systems . . . . . . . . . . . . . . . . 12
1.14 Safety measures when working on vehicles with air conditioning system and when using
refrigerant R 134a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.15 Basics for working on the refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2 General instructions for refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.1 Components of the refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.2 Extractor, filler and measurement valves for quick couplings of the AC service station on the
refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.3 Pressures and temperatures in the refrigerant circuit and its arrangement . . . . . . . . . . . . 24
2.4 Switch and sender on the refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.5 Electrical components which are not fitted on the refrigerant circuit . . . . . . . . . . . . . . . . . . 29
2.6 The inspection and measurement work can be performed using the pressure gauge . . . . 30
2.7 Air conditioning service and recycling equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.8 Repair and maintenance instructions for refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . 31
3 Legal texts and legal regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.1 Laws and regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.2 Verification procedure of refrigerant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4 Refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.1 Important repair instructions for air conditioning systems . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5 Working with the A/C service station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.1 Important instructions for working with the A/C Service station . . . . . . . . . . . . . . . . . . . . . . 37
5.2 Connecting the A/C service station to the refrigerant circuit for measuring and testing . . . . 38
5.3 Empty the refrigerant circuit with the A/C service station. . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.4 Evacuate the refrigerant circuit with the A/C service station. . . . . . . . . . . . . . . . . . . . . . . . . 39
5.5 Fill the refrigerant circuit with the A/C service station. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.6 Operate the air conditioning system after filling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.7 Fill refrigerant into the reservoir (filling cylinder or reservoir bottle) of the A/C service
station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.8 Draining the A/C service station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
6 Leak detection on the refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
6.1 Looking for leaks in the refrigerant circuit - important instructions . . . . . . . . . . . . . . . . . . . . 42
6.2 Leak detection on the refrigerant circuit with compressed air or nitrogen . . . . . . . . . . . . . . 43
6.3 Detecting leaks on the refrigerant circuit with the leak detector VAG1796 . . . . . . . . . . . . 45
6.4 Detecting leaks on the refrigerant circuit with the leak detector VAS 6196 or VAS 6201A
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7 Removing contaminants from the refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
7.1 Cleaning the refrigerant circuit with compressed air and nitrogen . . . . . . . . . . . . . . . . . . . . 52
7.2 Cleaning refrigerant circuit with refrigerant R134a (flush) . . . . . . . . . . . . . . . . . . . . . . . . . . 54
7.3 Principle circuit diagrams for different rinsing cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
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7.4 Adapter for setting up the rinsing cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
8 Complaints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
8.1 Possible complaints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
8.2 Temperature test of cooling capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
8.3 Odour from the heating and air conditioning unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
9 Check the pressure in the refrigerant circuit (with the A/C service station) . . . . . . . . . . . . 71
9.1 Test requirements before the pressure test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
9.2 Check pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
9.3 Continuation of the test depending on the arrangement of the refrigerant circuit . . . . . . . . 74
9.4 Pressure test for vehicles with throttle and catch pan (with AC compressor regulated from
the inside) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
9.5 Pressure test for vehicles with expansion valve and fluid reservoir (with AC compressor
regulated from the inside) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
9.6 Pressure test for vehicles with expansion valve, fluid reservoir and with regulating valve for
compressor of air conditioning system N280 (with AC compressor regulated from the
outside) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
10 Replace components of the refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
10.1 Replace parts on the refrigerant circuit - General instructions . . . . . . . . . . . . . . . . . . . . . . 91
10.2 Components of the refrigerant circuit leaking or damaged - the refrigerant circuit is absolutely
empty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
10.3 Components of the refrigerant circuit leaking or damaged - refrigerant is still in the refrigerant
circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
10.4 Replace AC compressor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
10.5 Replace catch pan and throttle/fluid reservoir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
11 Tools and materials, which are available from the importer . . . . . . . . . . . . . . . . . . . . . . . . 96
11.1 Setting up tools and materials which are available from the importer . . . . . . . . . . . . . . . . 96
11.2 A/C service station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
11.3 Flushing device for the refrigerant circuits 6337/1 or follow-up models (manufacturer Behr)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
11.4 Flushing device for the refrigerant circuits 6336/1 or follow-up models (manufacturer
Waeco) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
11.5 Leak detector V.A.G 1796 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
11.6 Leak detection system VAS 6196 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
11.7 Leak detection system VAS 6201A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
11.8 Adapter case of motor car set VAS 6338/1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
11.9 Case of release tools VAS 6127/3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
11.10 Socket insert T10364 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
12 Tools and materials, which are commercially available . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
12.1 Setting up tools and materials which are available from a dealer . . . . . . . . . . . . . . . . . . . . 100
12.2 Filling hoses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
12.3 Bottle connecting piece for pressure bottle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
12.4 Valve caps with replacement gaskets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
12.5 Pressure gauge with pressure reducer for nitrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
12.6 Quick-coupling adapter for service connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
12.7 Tools, which you make yourself . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
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Air conditioning system with refrigerant R134a - Edition 10.2014
ii Contents
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00 – Technical data
1 General notes on the air conditioning
system
(SRL000755; Edition 10.2014)
⇒ “1.1 Important instructions”, page 1
⇒ “1.2 Further documentation and information means”,
page 2
⇒ “1.3 Principles of the air-conditioning technology”, page 2
⇒ “1.4 Advantages of the air conditioning system - comfort”, page
4
⇒ “1.5 Operation of the air conditioning system”, page 4
⇒ “1.6 Refrigerant R134a”, page 5
⇒ “1.7 Vapour pressure table for refrigerant R134a”, page 6
⇒ “1.8 Properties of refrigerant R134a”, page 7
⇒ “1.9 Evidence of leaks”, page 8
⇒ “1.10 Refrigerant oil”, page 9
⇒ “1.11 General occupational safety”, page 9
⇒ “1.12 Using pressure tank”, page 11
⇒ “1.13 Safety precautions when working with extraction and fill‐
ing systems”, page 12
⇒ “1.14 Safety measures when working on vehicles with air con‐
ditioning system and when using refrigerant R 134a”, page 13
⇒ “1.15 Basics for working on the refrigerant circuit ”, page 14
1.1 Important instructions
This workshop manual provides basic knowledge to foremen and
mechanics, in order to carry out professional work on air condi‐
tioning systems for vehicles.
In order to carry out professional work on air conditioning systems
for vehicles, you must have worked through the content of this
Workshop Manual or completed a training course on the air con‐
ditioning system including general knowledge (possibly with a
corresponding final test) and you must be able to implement these
elements in practice.
Only these workers are recognised as qualified to pursue the ac‐
tivities on air conditioning systems for vehicles.
Note
♦
This workshop manual can also serve as training documen‐
tation.
♦ This Workshop Manual should be kept at the work place and
it must be submitted at the request of the responsible super‐
visory authority, if required.
♦ Alternative or additional regulations may be valid in certain
countries.
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1. General notes on the air conditioning system 1
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Caution
Non-approved tools or materials (e.g. stop leak additive) can
cause damage/deterioration to the system.
Only tools and materials approved by the manufacturer may
be used.
There is no guarantee if non-approved tools or materials were
used.
1.2 Further documentation and information
means
♦ Workshop manual for type related repair work ⇒ Heating, Air
Conditioning; Rep. gr. 87
♦ ⇒ Current flow diagrams, Electrical fault finding and Fitting lo‐
cations
♦ Self-study programmes, e.g. ⇒ Self-study programme No.
10 ; air conditioning system in the vehicle or ⇒ Self-study pro‐
gramme No. 25 ; Octavia - Climatronic
♦ Video programmes for occupational training
♦ ⇒ Electronic Catalogue of Original Parts
♦ ⇒ Catalogue of factory equipment and special tools
1.3 Principles of the air-conditioning tech‐
nology
⇒ “1.3.1 Physical principles”, page 2
⇒ “1.3.2 Heat always flows from a warmer substance to a colder
substance”, page 3
⇒ “1.3.3 Pressure and boiling point”, page 3
1.3.1 Physical principles
The four known aggregate phases of water also exist for the re‐
frigerants of the air conditioning system.
1 - gaseous (not visible)
2 - vaporous
3 - liquid
4 - solid
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If water is heated in a container (heat absorption) rising water
vapour is visible. If the vapour is heated even more through heat
absorption, the visible vapour becomes invisible gas. The proce‐
dure is reversible. If the heat content is extracted from the gas‐
eous water, this results first of all in vapour, from this the vapour
turns into water and then into ice.
A - Heat absorption
B - Heat dissipation
1.3.2 Heat always flows from a warmer sub‐
stance to a colder substance
Each substance consists of a mass of moving molecules. The fast
moving molecules of a warmer substance give up a part of their
energy to the molecules which are slower and have less heat.
This slows down the molecular movement of the warmer sub‐
stance and the molecular movement of the colder substance is
accelerated. This happens until the molecules of both substances
move with the same speed. Then they have the same tempera‐
ture and no further heat exchange takes place.
1.3.3 Pressure and boiling point
The boiling point of a liquid given in the tables always refers to
the atmospheric pressure of 1 bar. If the pressure of a liquid
changes, so does its boiling point.
It is known, for example, that water boils at lower temperatures
the lower the pressure.
Based on the vapour pressure curves for water and refrigerant
R134a it can be recognised, for example, that while maintaining
pressure, by lowering the temperature, the vapour turns to liquid
(in the condenser), or that, for example, by reducing the pressure,
the refrigerant turns from the liquid state into the vapour state
(evaporator).
Vapour pressure curve of water
A - liquid
B - gaseous
C - Vapour pressure curve of water
1 - Pressure of the liquid in bar (absolutely)
2 - Temperature in °C
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Vapour pressure curve of refrigerant R134a
A - liquid
B - gaseous
D - Vapour pressure curve of refrigerant R134a
1 - Pressure of the liquid in bar (absolutely)
2 - Temperature in °C
1.4 Advantages of the air conditioning sys‐
tem - comfort
One of the basic requirements for a concentrated and safe driving
is the feeling of comfort in the vehicle interior. This comfort is only
possible through the use of an air conditioning system, especially
in warm temperatures and at high humidity. Of course, opening
the windows, sunroof or allowing a greater flow of air through the
vehicle can contribute to well-being of occupants, but this also
has disadvantages in the vehicle interior, e.g.: additional noise,
draughts. exhaust fumes, unfiltered entry of pollen (unpleasant
for persons with allergies).
Through a controlled air conditioning system, in combination with
a well-designed heating and ventilation system, the feeling of
well-being and comfort can be achieved by controlling the indoor
temperature, humidity and air movement, according to the exter‐
nal conditions. This is possible when the vehicle is stationary as
well as when driving.
Further important advantages of the air conditioning system are:
♦ The cleaning of the air injected into the interior (by the wet fins
of the evaporator, for example, dust and pollen are washed
out and evacuated with the condensation water).
Temperatures in a mid-range car, e.g.: after a short period driving,
an outdoor temperature of 30 °C in the shade and the vehicle
under direct sunlight:
with air condition‐
ing system without air condi‐ tioning system
Head room 23 °C 42 °C
Chest 24 °C 40 °C
Footwell 30 °C 35 °C
1.5 Operation of the air conditioning system
The temperature in the passenger compartment is influenced by
radiant heat through the window and by the contact heat emitted
by metallic parts. In order to provide agreeable temperatures for
the passengers on very hot days, some of the ambient heat must
be evacuated.
As it is a well known fact that heat spreads towards colder tem‐
peratures, an aggregate that generates lower temperatures has
been fitted to the vehicle, i.e. the evaporator. Liquid refrigerant is
continuously evaporated in this aggregate. The heat required for
this operation is drawn from the air flowing through the evapora‐
tor.
The refrigerant gas together with the absorbed heat is pumped
out of the evaporator by the AC compressor. The AC compres‐
sor's compression work increases the heat content and the tem‐
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perature of the refrigerant. It is now considerably higher than the
ambient air temperature.
The high-temperature refrigerant and its heat content flow to the
condenser. There, because of the temperature difference be‐
tween the refrigerant and the ambient air, the refrigerant releases
heat into the ambient air via the condenser and liquefies.
The refrigerant is also a heat conveyor. As it will be re-used, it is
again pumped to the evaporator.
For this reason, the basic principle of all air conditioning systems
is a circuit for refrigerants. Differences arise in the composition of
the aggregates.
1.6 Refrigerant R134a
⇒ “1.6.1 Physical data of the refrigerant R134a”, page 5
⇒ “1.6.2 Trade names and designations of the refrigerant R134a”,
page 5
⇒ “1.6.3 Critical point”, page 6
⇒ “1.6.4 Environmental aspects of the refrigerant R134a”,
page 6
1.6.1 Physical data of the refrigerant R134a
The evaporation and condensation process is the procedure used
for all air conditioning systems in vehicles. Thus it works with a
lightly boiling substance, which is described as a refrigerant.
The refrigerant used is Tetrafluorethan R134a, which boils at
-26.5°C under a pressure of 1 bar.
Chemical formula CH2F-CF3 or CF3-CH2F
Chemical designation Tetrafluorethan
Boiling point at 1 bar -26.5°C
Solidification point -101.6°C
Critical temperature 100.6°C
Critical pressure 39.56 bar (absolutely)
1.6.2 Trade names and designations of the
refrigerant R134a
The refrigerant R134a is currently available under the following
trade names:
♦ H-FKW 134a
♦ SUVA 134a
♦ KLEA 134a
Note
♦
In other countries, other trade names may also be common.
♦ Among the wide range of different refrigerants, only this re‐
frigerant should be used for automobiles. The designation
“Frigen” or “Freon” are trade names. They also apply to re‐
frigerants that are not intended to be used for automobiles.
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1.6.3 Critical point
The critical point (critical temperature and critical pressure)
means that there is no divide over the same interface between
the surface of the liquid and the gas.
A substance is always gaseous when it is above its critical point.
At temperatures below the critical point, all types of refrigerants
in pressure tanks have a liquid and a gas phase, which means
that a gas blanket is present above the liquid.
As long as gas is still present in the tank aside from liquid, the
pressure depends upon the ambient temperature
⇒ “1.7 Vapour pressure table for refrigerant R134a”, page 6 .
1.6.4 Environmental aspects of the refrigerant
R134a
♦ R134a is a fluorinated hydrocarbon (PFC) and contains no
chlorine.
♦ R134a has a lower atmospheric lifetime than the refrigerant
R12.
♦ R134a does not attack the ozone layer.
♦ The contribution of R134a to the greenhouse effect is by a
factor of 10 less than the effect of the refrigerant R12.
1.7 Vapour pressure table for refrigerant
R134a
The vapour pressure table is decisive for each refrigerant used in
the literature for refrigeration technicians. From this table can be
read which vapour pressure above the liquid column in the vessel
pushes when the temperature of the reservoir is known.
As for any refrigerant a characteristic vapour pressure table is
known, knowledge of the refrigerant concerned can be obtained
by pressure and temperature measurement.
Temperature in °C Pressure in bar (overpressure)
R134a
-45 -0.61
-40 -0.49
-35 -0.34
-30 -0.16
-25 0.06
-20 0.32
-15 0.63
-10 1.00
-5 1.43
0 1.92
5 2.49
10 3.13
15 3.90
20 4.70
25 5.63
30 6.70
35 7.83
40 9.10
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Temperature in °C Pressure in bar (overpressure)
R134a
45 10.54
50 12.11
55 13.83
60 15.72
65 17.79
70 20.05
75 22.52
80 25.21
85 28.14
90 31.34
1.8 Properties of refrigerant R134a
⇒ “1.8.1 Colour”, page 7
⇒ “1.8.2 Vapour pressure”, page 7
⇒ “1.8.3 Air displacement as a result of gaseous refrigerant”, page
7
⇒ “1.8.4 Behaviour with metals”, page 7
⇒ “1.8.5 Behaviour with plastics”, page 8
⇒ “1.8.6 Critical temperature/critical pressure”, page 8
⇒ “1.8.7 Water content”, page 8
⇒ “1.8.8 Flammability”, page 8
⇒ “1.8.9 Filling factor”, page 8
1.8.1 Colour
As vapour and liquid, the refrigerant is as colourless as water, and
as gas it is invisible. Only the boundary layer between gas and
liquid is visible (fluid level in the standpipe of the filling cylinder or
bubbles in an inspection glass). In an inspection glass, the liquid
of the refrigerant R134a may appear coloured (milky). This opac‐
ity arises from a partially dissolved refrigerant oil and does not
indicate an error.
1.8.2 Vapour pressure
In a fully filled and closed reservoir, the vapour refrigerant that
evaporates on the surface is of the same volume which again
liquifies when the vapour particles fuse. This balanced status is
created under pressure and is frequently called vapour pressure.
The vapour pressure is temperature dependent
⇒ “1.7 Vapour pressure table for refrigerant R134a”, page 6
1.8.3 Air displacement as a result of gaseous
refrigerant
Refrigerant gas is heavier than air and therefore disperses along
the floor. It gathers in depressions where it displaces the available
air.
1.8.4 Behaviour with metals
In pure condition the refrigerant R134a is chemically stable and
does not corrode iron and aluminium. Contaminations of the re‐
frigerant, e.g. with chlorine compounds, may result in certain
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metals and plastics being corroded. This may lead to choking,
leaks or other deposits on the AC compressor piston.
1.8.5 Behaviour with plastics
Refrigerant is a solvent for certain plastics. These dissolved plas‐
tics may be eliminated during cooling in the expansion valve. This
may result in blockage of the valve. Therefore only use original
spare parts!
1.8.6 Critical temperature/critical pressure
Up to a gas pressure of 3.95 MPa (39.5 bar) overpressure (this
corresponds to a temperature of 101°C) refrigerant R134a re‐
mains chemically stable, above this temperature the refrigerant
decomposes see ⇒ “1.8.8 Flammability”, page 8 .
1.8.7 Water content
Water is only soluble in very small quantities in the liquid refrig‐
erant. As opposed to this refrigerant vapour and water vapour mix
in any proportion.
Water possibly present in the system is conveyed through the
refrigerant circuit as drops, once the dessicator in the fluid reser‐
voir has become saturated. The function of the dessicator is no
longer guaranteed. This water flows to the nozzle of the expan‐
sion valve where it turns to ice. This reduces the efficiency of the
cooling system.
Note
Water destroys the air conditioning system, as acids are produced
under high pressures and temperatures in combination with other
contaminations.
1.8.8 Flammability
Refrigerant is non-flammable. On the contrary it has a fire-retard‐
ant or fire extinguishing effect. Refrigerant decomposes when
brought into contact with flames or red-hot surfaces. UV light also
splits the refrigerant (generated during electrical welding). This
results in toxic fission products (hydrogen fluoride and traces of
carbonyl fluoride and fluorine), which give adequate advance
warning as they irritate the mucous membranes.
1.8.9 Filling factor
The reservoir must also include vapour space in addition to the
fluid space. As the temperature rises the fluid expands. The space
filled with vapour becomes smaller. At a given moment there will
only be fluid left in the reservoir. After this, only a minor temper‐
ature increase is required to generate very high pressures in the
reservoir as the fluid can no longer expand because there is no
more space. The resulting forces are great enough to burst the
reservoir. In order to ensure a reservoir is not over-filled, the pres‐
sure gas regulations stipulate how many kilos of refrigerant may
be filled per litre of inside volume of the reservoir. This “filling fac‐
tor” multiplied by the inside volume indicates the authorised filling
content. For the refrigerant R134a, it is 1.15°kg/l.
1.9 Evidence of leaks
The refrigerant circuit may start leaking because of external dam‐
age. Because of the small amount of leaked refrigerant, evidence
of minor leaks can be detected for example with an electronic leak
detector or leak detection additive which is filled into the refriger‐
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ant circuit. Leaks with less than 5 grams of refrigerant loss per
year can be detected with the electronic leak detector.
For the different refrigerants, leak detectors are used which are
designed for the composition of the relevant refrigerant. For ex‐
ample, leak detectors for refrigerant R12 are not suitable for
R134a, the refrigerant R134a has no chlorine atoms, this is why
these leak detectors do not respond.
1.10 Refrigerant oil
Refrigerant oil mixes (about 20 - 40 %, depending on the refrig‐
erant AC compressor type and refrigerant volume) with the re‐
frigerant, constantly circulates in the circuit and lubricates the
moving parts.
In combination with R134a air conditioning systems, special syn‐
thetic refrigerant oil, such as poly-alkyl-glycol (PAG) oil, is used.
This is necessary because, for example, mineral oil does not mix
with R134a. In addition, the materials of the R134a air condition‐
ing system are attacked if the mixture under pressure and high
temperatures flows through the refrigerant circuit or the lubricat‐
ing film in the AC compressor tears. The use of non-approved oils
results in the failure of the air conditioning system, therefore, only
approved oils may be filled in, see ⇒ Electronic Catalogue of
Original Parts .
Oil type for R134a in automobiles: PAG
Note
♦
Do not store refrigerant oil when it is open, because it is very
hygroscopic (water retentive).
♦ Always keep the oil reservoir closed.
♦ Do not use any used refrigerant oil. Because of its chemical
properties, refrigerant oil must not be disposed of with engine
oil or gearbox oil. Dispose of as used oil of unknown origin (see
waste, Environmental Protection, EU Regulation on refriger‐
ants 2037/2000).
⇒ “1.10.1 Properties of the refrigerant oil”, page 9
1.10.1 Properties of the refrigerant oil
The main properties have high dissolving power with refrigerant,
good lubricating properties, acid-free and very low in water con‐
tent.
The poly-alkylene-glycol (PAG) oils which are suitable for the re‐
frigerant R134a are strongly hygroscopic (water retentive) and
cannot be mixed with other oils. Therefore, to ensure protection
against penetrating humidity immediately close opened cans. Re‐
frigerant oil is contaminated by humidity and acids; it becomes
dark, viscous and corrodes metals.
1.11 General occupational safety
♦ Under current regulations and laws as well as in compliance
with the regulations of the Workers' Association.
♦ Observe occupational safety and job-related operating in‐
structions ⇒ Environmental Protection, Article 17 EU Regu‐
lation 2037/2000 . These must be hung out at the work place
for refrigerant.
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⇒ “1.11.1 Product features”, page 10
⇒ “1.11.2 Using refrigerant R 134a”, page 10
⇒ “1.11.3 Wear safety goggles”, page 10
⇒ “1.11.4 Wear protective gloves and apron”, page 10
⇒ “1.11.5 Do not breath in refrigerant vapours”, page 11
⇒ “1.11.6 Smoking ban”, page 11
⇒ “1.11.7 Welding and soldering”, page 11
⇒ “1.11.8 Pungent odour”, page 11
⇒ “1.11.9 First Aid”, page 11
1.11.1 Product features
Refrigerant which is used in the air conditioning systems for ve‐
hicles, belongs to the new generation of refrigerants which is
based on chlorine-free hydrofluorocarbon (HFC, R134a).
In regards to their physical behavior, this relates to under pres‐
sure liquefied refrigerant. They are subject to the pressure tank
regulation and must only be filled into approved and marked pres‐
sure gas tanks.
For safe and proper use, certain conditions which apply must be
respected.
1.11.2 Using refrigerant R 134a
WARNING
There is a risk through icing.
The refrigerant can leak as fluid or as vapour.
Do not open the reservoir in which the refrigerant is.
If the refrigerant reservoirs are opened, the contents can leak as
fluid or as vapour. This procedure is more intense the higher the
pressure is inside the reservoir.
How high the pressure is depends on two conditions:
• What type of refrigerant is filled in the reservoir. The rule is:
The lower the boiling point, the higher the pressure.
• How high the temperature is. The rule is: The higher the tem‐
perature, the higher the pressure.
1.11.3 Wear safety goggles
Wear safety goggles. It prevents that refrigerant gets into the eyes
and possibly severe damage caused by frostbite.
1.11.4 Wear protective gloves and apron
Refrigerants dissolve fats and oils pretty well. When in contact
with the skin, therefore remove the protective fat film. However,
degreased skin is sensitive to cold and disease germs.
Do not spill liquid refrigerant onto the skin. The heat to vapourise
extracts the refrigerant from the surrounding area. Thus, very low
temperatures can be achieved. This results in local frostbites
(boiling point of R134a ambient pressure at -26.5°C).
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1.11.5 Do not breath in refrigerant vapours
Note
In higher concentrations, escaping refrigerant vapours mix with
the surrounding air and replace the atmospheric oxygen neces‐
sary to breathe.
1.11.6 Smoking ban
Refrigerants may decompose in cigarette ash. The resulting sub‐
stances are toxic and should not be inhaled.
1.11.7 Welding and soldering
Note
Damaged or leaky components of the air conditioning system
must not be repaired by welding or soldering, however they must
be replaced.
Before welding and soldering on vehicles (in the vicinity of com‐
ponents of the air conditioning system) the refrigerant must be
drained off and the residues must be removed by blowing through
with compressed air and nitrogen.
The products of decomposition resulting from the refrigerant
through the effect of the heat are not only toxic, but are also highly
corrosive, so that pipes and components can be attacked. It is
essentially hydrogen fluoride.
1.11.8 Pungent odour
If the smell is pungent, then the mentioned products of decom‐
position have already formed. It must be avoided by all means to
breathe in these substances, otherwise damage to the respiratory
tract, lungs and other organs, could be the consequence.
1.11.9 First Aid
• On contact with eyes or mucous membranes, immediately
rinse extensively with running water and seek the attention of
an ophthalmologist.
• In case of contact with the skin, immediately remove conta‐
minated clothing and rinse the skin with plenty of water.
• During inhalation of refrigerant vapours at a higher concen‐
tration, bring those affected immediately to fresh air. Request
a physician. In case of respiratory disorder, give oxygen. If the
person concerned breathes only limitedly or not at all, tilt the
head backwards and give artificial respiration.
1.12 Using pressure tank
Secure bottles which are standing against falling, secure bottles
which are lying down against rolling away!
Do not throw the reservoir!
• When the reservoirs fall, they can become severely deformed
causing them to tear open. The refrigerant evaporates abrupt‐
ly, thus releasing considerable forces. Bottle parts which go
flying can cause serious injuries.
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• If improperly transported, the bottle valve can break off. To
protect the bottle valves, the bottles may only be transported
with the protective cap screwed on.
Do not place near radiators!
• Increased temperatures can occur next to the radiators. High‐
er temperatures also mean higher pressures, whereby the
permissible pressure for the reservoir can be exceeded.
Do not heat above 50°C
• In order to exclude a danger, the “pressure tank regulation”
stipulates that the reservoirs must not be heated above 50°C.
• Under no circumstances heat on an open flame. Through the
local overheating, structural changes can occur in the reser‐
voir material which reduce the pressure load of the reservoir.
Moreover, there is the danger of refrigerant decomposition by
local overheating.
Seal empty reservoirs
• In any case, empty refrigerant reservoirs must be sealed to
prevent any humidity from penetrating. Humidity leads to cor‐
rosion of reservoirs made of steel. This weakens the wall of
the reservoir. In addition, the rust particles which get into the
refrigeration plants from the reservoirs cause malfunctions.
1.13 Safety precautions when working with
extraction and filling systems
Caution
Operating instructions must be part of each extraction and fill‐
ing system, where the work procedure, the safety instructions
as well as the regulations are listed.
Prior to working with the extraction and filling system, acquaint
yourself with the safety instructions as well as the regulations
contained in the operating instructions and comply with them.
The operating instructions must always be readily available to
the staff, foremen and monitoring bodies.
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1.14 Safety measures when working on ve‐
hicles with air conditioning system and
when using refrigerant R 134a
WARNING
It is recommended to hold an eye bath flask within reach. If
liquid refrigerant gets into the eyes rinse the eyes out with water
for approximately 15 minutes.
Subsequently apply eye drops and immediately contact a
physician, even if the eyes are not painful. The physician must
be informed that the frostbites were caused by refrigerant
R134a.
The physician must be informed that the frostbites were
caused by refrigerant R134a. If in spite of these safety meas‐
ures refrigerant comes into contact with other body parts, rinse
immediately with water for at least 15 minutes.
If in spite of these safety measures refrigerant comes into con‐
tact with other body parts, rinse immediately with water for at
least 15 minutes.
Work on the air conditioning refrigerant circuit must only be
carried out in well-ventilated areas. Existing workshop suction
systems must be switched on.
Refrigerant must not be stored in lower areas (e.g. cellars) or
related exits or window openings.
During paint repairs, the temperature of the objects placed in
the drying oven or in its pre-heating zone must not exceed max.
80 °C (because heating causes a strong overpressure in the
system that may result in the opening of the pressure relief
valve).
Welding and soldering see
⇒ “1.11.7 Welding and soldering”, page 11 .
Never fill the containers completely with liquid refrigerant. With
sufficient expansion space (gas blanket) the container will
burst as the temperature rises with catastrophic consequences
⇒ “1.8 Properties of refrigerant R134a”, page 7 .
Refrigerant containers (e.g. filling cylinders at the A/C Service
position) must never be heated considerably or be exposed to
direct sunlight see ⇒ “1.12 Using pressure tank”, page 11 .
Under no circumstances should refrigerant be filled into sys‐
tems and reservoirs in which there is air (evacuate systems
and reservoirs before filling with refrigerant).
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1.15 Basics for working on the refrigerant cir‐
cuit
⇒ “1.15.1 General points”, page 14
⇒ “1.15.2 Removing contaminants from the refrigerant circuit ”,
page 14
⇒ “1.15.3 Additional work on vehicles with AC compressor without
magnetic coupling ”, page 15
⇒ “1.15.4 O-ring seals”, page 15
⇒ “1.15.5 Work procedure before operating the air conditioning
system after a repair”, page 15
1.15.1 General points
♦ Keep the work area and all tools clean.
♦ Wear work clothes, protective goggles and gloves when han‐
dling refrigerant and nitrogen.
♦ Switch on all available exhaust systems in the workshop.
♦ Use an A/C Service position only to empty the refrigerant cir‐
cuit, only then may you open the screwed connections and
replace defective components.
♦ Seal off opened aggregates and hoses immediately with caps
to protect them against humidity and dirt.
♦ Only use tools and materials intended for refrigerant R134a.
♦ Protect the refrigerant oil from humidity by closing opened
cans.
Note
♦
After completing repair works, screw on screw caps on all the
suction-, filler valves and service connections (with gaskets).
♦ Before operating the air conditioning system, observe the ve‐
hicle-specific filling contents.
♦ Do not top up with refrigerant, drain existing refrigerant and
refill the system.
1.15.2 Removing contaminants from the refrig‐
erant circuit
Flush the refrigerant circuit with R134a (if necessary blow
through), if:
– Humidity or dirt has penetrated into the refrigerant circuit (e.g.
after an accident).
– The refrigerant has become dark and thick.
– After an A/C compressor replacement there is too much re‐
frigerant oil in the refrigerant circuit.
– The air conditioning compressor must be replaced because of
internal damage (e.g. it is too laud, jammed or no output).
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Note
Remove contaminants from the refrigerant circuit
⇒ “7 Removing contaminants from the refrigerant circuit”,
page 52 .
1.15.3 Additional work on vehicles with AC
compressor without magnetic coupling
Note
♦ The engine must only be started if the refrigerant circuit is cor‐
rectly assembled (A/C compressor operates).
♦ If possible, only start the engine if the refrigerant circuit is filled.
♦ The engine must on no account be started if vacuum is present
in the refrigerant circuit (in case of evacuating with an A/C
service station). This would result in mechanical damage of
the A/C compressor.
♦ If the engine runs with an empty refrigerant circuit (no vacuum
must be present in the circuit), an increase in its revolutions
must be absolutely avoided. There must be at least a quarter
of the refrigerant oil volume present in the AC compressor,
which is prescribed for this refrigerant circuit and the engine
may be run for max. 10 minutes.
♦ So that the AC compressor suffers no damage when the re‐
frigerant circuit is empty, it is fitted with a secured oil supply.
This means that approx. 40 to 50 cm3 of refrigerant oil remains
in the AC compressor.
1.15.4 O-ring seals
These O-rings seal off the connection points between the indi‐
vidual components of the refrigerant circuit.
Only use O-rings that are resistant to refrigerant R134a and re‐
lated refrigerant oils. Original spare parts offer this guarantee.
Black and coloured O-rings are fitted.
O-ring seals:
♦ Only use once, replace.
♦ Pay attention to correct diameter -a- and -b-.
♦ Moisten with refrigerant oil before inserting.
1.15.5 Work procedure before operating the air
conditioning system after a repair
– Turn the A/C compressor on the clutch or the belt pulley of the
magnetic coupling about 10 revolutions by hand.
– Start the engine with the air conditioning system deactivated
( air conditioner magnetic coupling - N25- and regulating valve
for compressor of air conditioning system - N280- are not ac‐
tivated).
– After the idling speed has stabilised, switch on the AC com‐
pressor and operate it for at least 10 minutes at idle speed and
at maximum refrigerating capacity.
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2 General instructions for refrigerant
circuit
⇒ “2.1 Components of the refrigerant circuit”, page 16
⇒ “2.2 Extractor, filler and measurement valves for quick cou‐
plings of the AC service station on the refrigerant circuit”,
page 22
⇒ “2.3 Pressures and temperatures in the refrigerant circuit and
its arrangement”, page 24
⇒ “2.4 Switch and sender on the refrigerant circuit”, page 28
⇒ “2.5 Electrical components which are not fitted on the refrigerant
circuit”, page 29
⇒ “2.6 The inspection and measurement work can be performed
using the pressure gauge”, page 30
⇒ “2.7 Air conditioning service and recycling equipment ”,
page 31
⇒ “2.8 Repair and maintenance instructions for refrigerant circuit”,
page 31
2.1 Components of the refrigerant circuit
⇒ “2.1.1 Distribution of the components of the refrigerant circuit
and their influence on the high- and low-pressure side”,
page 17
⇒ “2.1.2 AC compressor”, page 18
⇒ “2.1.3 Condenser”, page 19
⇒ “2.1.4 Fluid reservoir with dessicator”, page 19
⇒ “2.1.5 Evaporator”, page 20
⇒ “2.1.6 Throttle”, page 20
⇒ “2.1.7 Expansion valve”, page 21
⇒ “2.1.8 O-ring seals”, page 21
⇒ “2.1.9 Pipes and hoses of the refrigerant circuit”, page 21
⇒ “2.1.10 Pressure relief valve”, page 21
Caution
Non-approved tools or materials (e.g. stop leak additive) can
cause damage/deterioration to the system.
Only tools and materials approved by the manufacturer may
be used.
There is no guarantee if non-approved tools or materials were
used.
• All the components of the refrigerant circuit, which are sent in
for quality monitoring, must always be closed (use original
screw caps of the original part).
• Replace damaged or leaky components of the refrigerant cir‐
cuit.
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