Get General information on air conditioning systems Guide for Audi A2 SUV 1999-2005

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

2

General information on air condition‐

ing systems

⇒ “2.1 General notes”, page 4

⇒ “2.2 Introduction”, page 4

⇒ “2.3 Safety precautions for vehicles with start/stop system”,

page 6

⇒ “2.4 Other reference material ”, page 6

⇒ “2.5 Principles of air conditioning systems”, page 7

⇒ “2.6 Refrigerant R134a”, page 9

⇒ “2.7 Properties of refrigerant R134a”, page 11

⇒ “2.8 Refrigerant oil”, page 13

⇒ “2.9 How air conditioning works”, page 14

⇒ “2.10 General work safety”, page 15

⇒ “2.11 Product properties”, page 16

⇒ “2.12 Handling refrigerant”, page 16

⇒ “2.13 Handling pressure vessels”, page 17

⇒ “2.14 Safety regulations for working with extraction and charg‐

ing systems”, page 18

⇒ “2.15 Safety measures for working on vehicles with air condi‐

tioning system and for handling refrigerant R134a”, page 18

⇒ “2.16 Basic rules for working on refrigerant circuit”, page 22

⇒ “2.17 Before using air conditioner after system has been re-

charged”, page 27

2.1

General notes

⇒ “2.2 Introduction”, page 4

⇒ “2.4 Other reference material ”, page 6

⇒ “2.5 Principles of air conditioning systems”, page 7

⇒ “2.6 Refrigerant R134a”, page 9

⇒ “2.7 Properties of refrigerant R134a”, page 11

⇒ “2.8 Refrigerant oil”, page 13

⇒ “2.9 How air conditioning works”, page 14

⇒ “2.10 General work safety”, page 15

⇒ “2.11 Product properties”, page 16

⇒ “2.12 Handling refrigerant”, page 16

⇒ “2.13 Handling pressure vessels”, page 17

⇒ “2.14 Safety regulations for working with extraction and charg‐

ing systems”, page 18

⇒ “2.15 Safety measures for working on vehicles with air condi‐

tioning system and for handling refrigerant R134a”, page 18

⇒ “2.16 Basic rules for working on refrigerant circuit”, page 22

⇒ “2.17 Before using air conditioner after system has been re-

charged”, page 27

2.2

Introduction

4

Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

This manual is intended to provide foremen and mechanics with

the basic knowledge needed to ensure reliable and successful

repairs.

Note

This requires careful study of the manual, coupled with suitable

training on automotive air conditioning systems (with a qualifica‐

tion test if applicable) and the ability to apply the acquired exper‐

tise in practice.

This document is a compact reference work which should be kept

at the workplace. It should also be available for presentation to

the responsible supervisory agency on request.

Vehicles with high-voltage system (hybrid vehicles)

High voltage! Danger to life!

The voltage levels in the high-voltage system constitute a safety

hazard. Danger of severe or fatal injuries from electric shock if

high-voltage components or high-voltage wiring are damaged.

– Carry out visual check of high-voltage components and high-

voltage wiring.

– Never use cutting/forming tools or other sharp-edged imple‐

ments.

– Never perform work using welding, brazing, thermal bonding

or hot air.

Risk of injury - engine may start unexpectedly

It is difficult to determine whether the drive system of an electric

vehicle or hybrid vehicle is active. Moving parts can trap or draw

in parts of the body.

– Switch off ignition.

– Place ignition key outside vehicle.

Risk of damage to high-voltage wiring

Incorrect handling may result in damage to the insulation of high-

voltage wires or high-voltage connectors.

– Never use high-voltage wiring or high-voltage connectors as

a support.

– Never prop tools against high-voltage wiring or high-voltage

connectors.

– Never bend or kink high-voltage wiring.

– Pay attention to coding when connecting high-voltage con‐

nections.

Observe the additional warnings for working on vehicles with

high-voltage electrical system.

⇒ “1 Warning instructions when working on vehicles with high-

voltage system”, page 1

2. General information on air conditioning systems

5

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

Vehicles with start/stop system

Risk of injury - engine may start unexpectedly

The engine can start unexpectedly if the vehicle's start/stop sys‐

tem is activated. A message in the instrument cluster indicates

whether the start/stop system is activated.

– To deactivate the start/stop system, switch off the ignition.

All vehicles

Caution

Tools or materials (e.g. sealing additives) that have not been

approved can damage or impair the system.

Use only tools and materials that have been approved by the

manufacturer.

Warranty claims are not accepted if tools or materials that have

not been approved are used.

2.3

Safety precautions for vehicles with start/stop system

Risk of injury - engine may start unexpectedly

The engine can start unexpectedly if the vehicle's start/stop sys‐

tem is activated. A message in the instrument cluster indicates

whether the start/stop system is activated.

– To deactivate the start/stop system, switch off the ignition.

2.4

Other reference material

♦ Workshop Manual for model-specific maintenance work ⇒

Heating, air conditioning; Rep. gr. 87 ; Overview of fitting lo‐

cations - air conditioner (vehicle-specific Workshop Manual)

and ⇒ Current flow diagrams, Electrical fault finding and Fitting

locations

♦ Technical Service Handbook (TPI) outlining action to be taken

to rectify current problems

♦ Self-study programmes, e.g. ⇒ Self-study programme No.

208 ; Air conditioning systems in motor vehicles

♦ Video training courses for dealerships

♦ List of special tools and workshop equipment required for re‐

pairing the air conditioner ⇒ Electronic parts catalogue (Tools;

Workshop equipment/tools; Air conditioner/heater).

♦ Service Organisation Handbook, Vol. 1 “Additional equipment”

⇒ Audi ServiceNet, Handbooks

♦ Workshop Manual: Air conditioner with refrigerant R12 (for

vehicles built up to model year 1993; this Workshop Manual is

available in hardcopy form only)

Vehicles with high-voltage system (hybrid vehicles)

For all work on vehicles with high-voltage system, note warnings

for vehicles with high-voltage system

6

Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

⇒ “1 Warning instructions when working on vehicles with high-

voltage system”, page 1 .

2.5

Principles of air conditioning systems

⇒ “2.5.1 Physical principles”, page 7

⇒ “2.5.2 Pressure and boiling point”, page 7

⇒ “2.5.3 Vapour pressure table for refrigerant R134a”,

page 8

⇒ “2.7 Properties of refrigerant R134a”, page 11

2.5.1

Physical principles

The four familiar states of water apply to air conditioning refriger‐

ants, too.

1 - Gas (invisible)

2 - Vapour

3 - Liquid

4 - Solid

When water is heated in a vessel (heat absorption), water vapour

can be seen to rise. If the vapour is further heated through heat

absorption, the visible vapour turns into invisible gas. The process

is reversible. If heat is extracted from gaseous water -A-, it

changes first to vapour -B-, then to water and finally to ice.

A - Heat absorption

B - Heat emission

Heat always flows from a warmer to a colder substance

Every substance consists of a mass of moving molecules. The

fast-moving molecules of a warmer substance give off some of

their energy to the cooler and thus slower molecules. As a result,

the molecular motion of the warmer substance slows down and

that of the colder substance is accelerated. This process contin‐

ues until the molecules of both substances are moving at the

same speed. They are then at the same temperature and no fur‐

ther heat exchange takes place.

2.5.2

Pressure and boiling point

The boiling point given in tables for a liquid is always referenced

to an atmospheric pressure of 1 bar. If the pressure acting on a

liquid changes, its boiling point also changes.

2. General information on air conditioning systems

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

Note

Pressure can be measured in various units: 1 MPa (megapascal)

is equivalent to 10 bar gauge pressure, or 145 psi; 1 bar absolute

pressure is the same as 0 bar gauge pressure, which is roughly

equivalent to atmospheric pressure.

For example, water boils at a lower temperature the lower the

pressure.

The vapour pressure curves for water and refrigerant R134a

show, for example, that, at constant pressure, reducing the tem‐

perature changes vapour to liquid (in the condenser) or that, for

instance, reducing the pressure causes the refrigerant to change

from liquid to vapour (in the evaporator).

Vapour pressure curve for water

A - Liquid

B - Gaseous

C - Vapour pressure curve for water

1 - Pressure acting on liquid in bar (absolute)

2 - Temperature in °C

Vapour pressure curve for refrigerant R134a

A - Liquid

B - Gaseous

D - Vapour pressure curve for refrigerant R134a

1 - Pressure acting on liquid in bar (absolute)

2 - Temperature in °C

2.5.3

Vapour pressure table for refrigerant

R134a

The vapour pressure table for every refrigerant is published in the

literature for refrigeration system engineers. This table makes it

possible to determine the vapour pressure acting on the column

of liquid in a vessel if the temperature of the vessel is known.

As there is a characteristic vapour pressure table for every refrig‐

erant, it is possible to identify the type of refrigerant by measuring

pressure and temperature.

8

Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

Note

♦ “0 bar absolute pressure” corresponds to an absolute vacuum.

The normal ambient pressure (atmospheric pressure) corre‐

sponds to approx. “1 bar absolute pressure”. On the scales of

most pressure gauges, “0 bar” corresponds to an absolute

pressure of 1 bar (this is also indicated by the value “-1” ap‐

pearing below “0”).

♦ Pressure can be measured in various units: 1 MPa (mega‐

pascal) is equivalent to 10 bar gauge pressure, or 145 psi; 1

bar absolute pressure is the same as 0 bar gauge pressure,

which is roughly equivalent to atmospheric pressure.

Temperature in °C

Pressure in bar (gauge pres‐

sure), R134a

-45

-40

-35

-30

-25

-20

-15

-10

-5

-0.61

-0.49

-0.34

-0.16

0.06

0.32

0.63

1.00

1.43

0

1.92

5

2.49

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

3.13

3.90

4.70

5.63

6.70

7.83

9.10

10.54

12.11

13.83

15.72

17.79

20.05

22.52

25.21

28.14

31.34

2.6

Refrigerant R134a

Air conditioning systems in vehicles use a vaporisation and con‐

densation process. These systems employ a substance with a

low boiling point, referred to as refrigerant.

The refrigerant used is tetrafluoroethane or R134a, which boils at

-26.5°C at a vapour pressure of “1 bar absolute pressure” (cor‐

responds approx. to ambient pressure).

2. General information on air conditioning systems

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Air conditioner with refrigerant R134a - Edition 11.2018

⇒ “2.6.1 Physical properties of refrigerant R134a”, page 10

⇒ “2.6.2 Critical point”, page 10

⇒ “2.6.3 Environmental aspects of refrigerant R134a”,

page 10

2.6.1

Physical properties of refrigerant R134a

Chemical formula

Chemical designation

Boiling point at 1 bar

Solidification point

Critical temperature

Critical pressure

CH2F–CF3 or CF3–CH2F

Tetrafluoroethane

-26.5 °C

-101.6 °C

100.6 °C

40.56 bar (absolute)

2.6.2

Critical point

The critical point (critical temperature and critical pressure) is the

point above which there is no longer a boundary between liquid

and gas.

A substance above its critical point is always in the gaseous state.

At temperatures below the critical point, all types of refrigerant in

pressure vessels exhibit both a liquid and a gas phase, i.e. there

is a layer of gas above the liquid.

As long as both liquid and gas are present in the vessel, the pres‐

sure is governed by ambient temperature ⇒ page 8 “Vapour

pressure table”.

Note

Different types of refrigerant must never be mixed. The refrigerant

specified for the respective air conditioning system must be used

exclusively.

2.6.3

Environmental aspects of refrigerant

R134a

♦ R134a is a fluorocarbon and contains no chlorine.

♦ R134a has a shorter atmospheric lifespan than refrigerant

R12.

♦ R134a does not damage the ozone layer; the ozone-depleting

potential is zero.

♦ The global warming potential (GWP) of R134a is approx. 1400

(GWP of carbon dioxide = 1). To reduce the impact of refrig‐

erant R134a on global warming, the European Commission

has ruled that vehicles with air conditioners using refrigerant

with a GWP higher than 150 may no longer be made available

on the market from 1 January 2017 onwards. Air conditioners

in vehicles which were made available on the market before

31 December 2016 may be filled and operated with refrigerant

R134a until further notice.

♦ The global warming effect of R134a is ten times less than that

of refrigerant R12.

10

Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

2.7

Properties of refrigerant R134a

⇒ “2.7.1 Trade names and designations”, page 11

⇒ “2.7.2 Colour”, page 11

⇒ “2.7.3 Vapour pressure”, page 11

⇒ “2.7.4 Physical properties of R134a”, page 11

⇒ “2.7.5 Reaction with metals”, page 12

⇒ “2.7.6 Critical temperature/critical pressure”, page 12

⇒ “2.7.7 Water content”, page 12

⇒ “2.7.8 Combustibility”, page 12

⇒ “2.7.9 Charge factor”, page 12

⇒ “2.7.10 Tracing leaks”, page 12

2.7.1

Trade names and designations

The refrigerant R134a is currently available under the following

trade names:

♦ H-FKW 134a

♦ SUVA 134a

♦ KLEA 134a

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

should not be used in vehicles.

2.7.2

Colour

Like water, refrigerants are colourless in both vapour 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 a sight glass). Liquid refrigerant R134a may have a coloured

(milky) appearance in a sight glass. This cloudiness is caused by

partially dissolved refrigerant oil and does not indicate a fault.

2.7.3

Vapour pressure

In a partially filled, closed vessel, the quantity of refrigerant evap‐

orating from the surface equals the quantity returning to the liquid

state as vapour particles condense. This state of equilibrium oc‐

curs when the system is pressurised and is often called vapour

pressure. Vapour pressure is dependent on temperature

⇒ page 8 “Vapour pressure table”.

2.7.4

Physical properties of R134a

As the vapour pressure curves of R134a and other refrigerants

are sometimes very similar, a clear identification is not possible

based merely on the pressure.

When using R134a, the air conditioner compressor is lubricated

with special synthetic refrigerant oils, e.g. PAG oils (polyalkylene

glycol oils).

2. General information on air conditioning systems

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

2.7.5

Reaction with metals

In its pure state, refrigerant R134a is chemically stable and does

not corrode iron or aluminium.

However, refrigerant impurities such as chlorine compounds

cause corrosion of certain metals and plastics. This can cause

blockages, leaks and deposits on the air conditioner compressor

piston.

2.7.6

Critical temperature/critical pressure

The refrigerant R134a remains chemically stable up to a gas

pressure of 39.5 bar (40.56 bar absolute pressure; corresponds

to a temperature of 101 °C). Above this temperature, the refrig‐

erant decomposes (see "Combustibility").

2.7.7

Water content

Only very small amounts of water are soluble in liquid refrigerant.

In contrast, refrigerant vapour and water vapour mix in any ratio.

Any water in the refrigerant circuit will be entrained in droplet form

once the dryer in the receiver or reservoir has absorbed approx.

7 g of water. This water flows as far as the expansion valve nozzle

or the restrictor and turns to ice. The air conditioner will then no

longer provide any cooling effect.

Water causes irreparable damage to the air conditioner because

at high pressures and temperatures it combines with other im‐

purities to form acids.

2.7.8

Combustibility

Refrigerant is non-flammable. In fact it has a fire-inhibiting or fire-

extinguishing effect. Refrigerant decomposes when exposed to

flames or red-hot surfaces. UV light (produced for example during

electric welding) also causes refrigerant decomposition. The re‐

sultant decomposition products are toxic and must not be inhaled.

However, these chemicals irritate the mucous membranes, giving

adequate warning of their presence.

2.7.9

Charge factor

A container must have space for vapour as well as liquid. As the

temperature rises, the liquid expands. The vapour-filled space

becomes smaller. At a certain point, there will only be liquid in the

vessel. Beyond this, even a slight increase in temperature causes

great pressure to build up in the vessel as the liquid attempts to

continue expanding despite the absence of the necessary space.

The resultant forces are sufficient to rupture the vessel. To stop

containers being overfilled, regulations governing the storage of

compressed gases specify the number of kilograms of refrigerant

with which a container may be filled per litre of internal volume.

The maximum permissible capacity is calculated by multiplying

this "charge factor" by the internal volume of the vessel. The

charge factor for refrigerant used in motor vehicles is 1.15 kg/litre.

2.7.10

Tracing leaks

External damage, for example, can cause a leak in the refrigerant

circuit. Minor leaks where only a small amount of refrigerant is

escaping can be detected using, for example, an electronic leak

detector or by adding a UV leak detection additive to the refrig‐

erant circuit. Electronic leak detectors are capable of registering

leaks with refrigerant losses of less than 5 g per year.

12

Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

Note

It is important to use leak detectors that are designed for the

composition of the respective refrigerant type. For example, a

leak detector for R12 refrigerant is not suitable for R134a refrig‐

erant because R134a has no chlorine atoms and the leak detector

therefore does not respond.

2.8

Refrigerant oil

Caution

♦ For information on how to handle refrigerant oil, refer to ⇒

Audi ServiceNet, HSO Environmental Protection (or ⇒

Volkswagen ServiceNet, Handbooks, Service Handbook;

Environmental Protection ) and observe local regulations.

Refrigerant oil mixes with the refrigerant (in a ratio of about

20 - 40 %, depending on compressor type and quantity of refrig‐

erant) and circulates constantly in the system, lubricating the

moving parts.

Special synthetic refrigerant oils, e.g. polyalkylene glycol (PAG)

oil, are used in conjunction with R134a air conditioning systems.

This is necessary as mineral oil, for example, does not mix with

R134a. In addition, the materials of the R134a air conditioning

system could be corroded as a result of mixture flowing through

the refrigerant circuit under pressure at high temperatures or

breakdown of the lubricating film in the air conditioner compres‐

sor. The use of non-approved oils can lead to the failure of the air

conditioning system, so it is important to use only the approved

types of oil.

⇒ Electronic parts catalogue

Type of oil for R134a in motor vehicles: PAG (polyalkylene-glycol)

Note

♦ Do not store refrigerant oil in open containers as it is extremely

hygroscopic (it attracts water).

♦ Always keep oil containers sealed.

♦ Do not re-use old refrigerant oil. Refrigerant oil must be dis‐

posed of as used oil of unknown origin (observe local regula‐

tions) ⇒ Audi ServiceNet, HSO Environmental Protection (or

⇒ Volkswagen ServiceNet, Handbooks, Service Handbook;

Environmental Protection ).

♦ Ester-based oils are currently only intended for use with large

systems (not for motor vehicle air conditioners).

⇒ “2.8.1 Properties of refrigerant oil”, page 13

2.8.1

Properties of refrigerant oil

The most important properties are a high degree of solubility with

refrigerant, good lubricity, absence of acid and minimal water

content. It is therefore only permissible to use certain oils. For a

list of approved refrigerant oils and capacities, refer to

⇒ page 333 .

PAG oils for refrigerant R134a are highly hygroscopic and do not

mix with other oils. Opened containers should therefore be closed

again immediately to prevent moisture from entering. Moisture

2. General information on air conditioning systems

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

and acids cause refrigerant oil to age, making it dark, viscous and

corrosive to metals.

Note

♦ Due to its chemical properties, refrigerant oil must not be dis‐

posed of together with engine oil or gear oil. Refrigerant oil

must be disposed of as used oil of unknown origin (observe

local regulations) ⇒ Audi ServiceNet, HSO Environmental

Protection (or ⇒ Volkswagen ServiceNet, Handbooks, Service

Handbook; Environmental Protection ).

♦ Only oil approved for the air conditioner compressor may be

used for refrigerant circuits containing refrigerant R134a ⇒

Electronic parts catalogue and capacities ⇒ page 333 .

Important information:

As refrigerant oil is extremely hygroscopic, open containers must

be closed and re-sealed immediately after use to prevent mois‐

ture from entering.

Note

♦ A use-by date for the refrigerant oil is stated on the bottle in

which the refrigerant oil is supplied.

♦ This date is not relevant if the bottle is sealed air-tight.

♦ If the bottle is sealed air-tight, the refrigerant oil can also be

used after the date stated on the bottle.

2.9

How air conditioning works

The temperature in the passenger compartment depends on the

amount of heat radiated into the vehicle through the windows and

conducted by the metal parts of the body. In hot weather some of

the heat must be pumped off to achieve a more comfortable tem‐

perature for the occupants.

As heat is always transmitted away from warmer areas and into

cooler areas, the passenger compartment is fitted with a unit for

generating low temperatures in which refrigerant is constantly

evaporated. The heat required for this is extracted from the air

flowing through the evaporator.

After absorbing heat, the refrigerant is pumped off by the air con‐

ditioner compressor. Thanks to the action of the compressor, the

heat content and temperature of the refrigerant increases. Its

temperature is then substantially higher than that of the surround‐

ing air.

The hot refrigerant flows with its heat content to the condenser.

where the refrigerant dissipates its heat to the surrounding air via

the condenser due to the temperature gradient between the re‐

frigerant and the surrounding air.

The refrigerant thus acts as a heat transfer medium. As it will be

needed again, the refrigerant is returned to the evaporator.

For this reason all air conditioning systems are based on the re‐

frigerant circulation principle. There are however differences as

regards the units used.

14

Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

⇒ “2.9.1 Comfort of vehicle occupants”, page 15

⇒ “2.9.2 Environmental aspects”, page 15

2.9.1

Comfort of vehicle occupants

A basic requirement for safety and concentration while driving is

a feeling of comfort in the passenger compartment. Especially

when conditions are hot and humid, a good level of comfort can

only be achieved with air conditioning. Passenger comfort can of

course also be improved by opening the windows or sun roof, or

by increasing the air flow. This, however, involves several draw‐

backs for the occupants, e.g. more noise, draughts, exhaust

fumes and unfiltered pollen (unpleasant for allergy sufferers).

Climate control together with a good heating and ventilation sys‐

tem can create a sense of well-being and comfort by regulating

temperature, humidity and air circulation in the passenger com‐

partment to suit ambient conditions, both when the vehicle is

stationary and when it is moving.

Other important advantages of air conditioning:

♦ Filtration of the air supplied to the passenger compartment

(dust and pollen, for example, are washed out by the moist fins

of the evaporator and discharged with the condensation).

♦ Pleasant temperature levels (example: mid-size car after short

travelling time, ambient temperature 30 °C in the shade and

vehicle exposed to sunlight)

With air conditioning Without air condi‐

tioning

At head height

At chest level

In footwell

23 °C

24 °C

30 °C

42 °C

40 °C

35 °C

2.9.2

Environmental aspects

Since about 1992, the air conditioning systems of newly manu‐

factured cars have been successively changed to refrigerant

R134a. This refrigerant contains no chlorine and therefore does

not deplete the ozone layer.

Up until roughly 1992, refrigerant R12 was used for air condition‐

ing systems. Due to its chlorine atoms, this CFC had a high ozone

depletion potential as well as potential for intensifying the green‐

house effect.

Conversion programmes are available for old existing systems

filled with the ozone-depleting substance R12 ⇒ Workshop Man‐

ual for air conditioners with refrigerant R12 (this Workshop Man‐

ual is available in hardcopy form only).

The global warming potential (GWP) of R134a is approx. 1400;

the European Commission has therefore ruled that vehicles using

this refrigerant may no longer be made available on the market

from 1 January 2017 onwards ⇒ page 10 . From 2016 onwards,

refrigerant with a GWP of less than 150 will be used for newly

manufactured vehicles (e.g. refrigerant R1234yf with a GWP of

less than 5).

For environmental reasons, refrigerants must not be released into

the atmosphere ⇒ page 73 (see the relevant environmental leg‐

islation).

2.10

General work safety

♦ In accordance with regulations of the German industrial liabil‐

ity insurance association, VBG 20, (other regulations may

apply in other countries)

2. General information on air conditioning systems

15

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Air conditioner with refrigerant R134a - Edition 11.2018

♦ Observe specific instructions relating to workplaces where re‐

frigerants are handled ⇒ Audi-ServiceNet, HSO Environmen‐

tal Protection . These instructions must be posted at the

workplace.

2.11

Product properties

Refrigerants used in motor vehicle air conditioning systems be‐

long to the new generation of refrigerants based on chlorine-free,

partially fluorinated hydrocarbons (H-FKW, R134a; other names

may be used in other countries).

With regard to their physical properties, these are refrigerants

which have been liquefied under pressure. They are subject to

the regulations governing pressure vessels and may only be used

in approved and appropriately marked containers.

Specific requirements must be observed to ensure safe and prop‐

er handling:

2.12

Handling refrigerant

If refrigerant vessels are opened, the contents may escape in liq‐

uid or vapour form. The higher the pressure in the vessel, the

more vigorous the process.

The pressure level is governed by two factors:

•

The type of refrigerant in the vessel. “Rule: The lower the boil‐

ing point, the higher the pressure.”

•

The temperature level. “Rule: The higher the temperature, the

higher the pressure.”

WARNING

♦ Risk of injury (frostbite).

♦ The refrigerant may escape as liquid or vapour.

♦ Do not open vessels containing refrigerant.

Wear safety goggles.

Put on safety goggles to prevent refrigerant getting into the eyes,

as this could cause severe injury through frostbite.

Wear protective gloves and apron.

Grease and oils dissolve readily in refrigerants. They would there‐

fore damage the protective layer of grease if allowed to come into

contact with the skin. Degreased skin is however sensitive to the

cold and germs.

Do not allow liquid refrigerant to come into contact with the skin

The refrigerant draws heat for evaporation from the surrounding

area - even if this is the skin. This may give rise to extremely low

temperatures and result in local frostbite (boiling point of R134a:

-26.5 °C at ambient pressure).

Do not inhale refrigerant vapours

If refrigerant vapour escapes in concentrated form, it mixes with

the surrounding air and displaces the oxygen necessary for

breathing.

Smoking is absolutely prohibited

A burning cigarette can cause refrigerant to decompose. The re‐

sultant substances are toxic and must not be inhaled.

16

Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

Welding and soldering on refrigeration systems

Before performing welding, brazing or soldering work on vehicles

in the vicinity of air conditioning system components, extract re‐

frigerant and remove any remaining refrigerant by blowing out

with nitrogen.

The products of refrigerant decomposition due to the effect of heat

are not only toxic, but may also have a highly corrosive effect on

pipes and system components. The principal substance is hydro‐

gen fluoride.

Pungent odour

A pungent odour indicates that the products of decomposition

mentioned above have already formed. Do NOT inhale these

substances, otherwise the respiratory tract, lungs and other or‐

gans could be damaged.

First aid

•

Following accidental contact with eyes or mucous mem‐

branes, immediately rinse with copious amounts of running

water and consult an eye specialist.

Following accidental contact with the skin, immediately re‐

move clothing affected and rinse skin with copious amounts of

water.

Following accidental inhalation of concentrated refrigerant va‐

pours, the person concerned must be taken immediately into

the open air. Call a doctor. Administer oxygen in the event of

breathing difficulties. If the person affected is having great dif‐

ficulty breathing or is not breathing at all, tilt back head and

administer artificial respiration.

⇒ “2.13 Handling pressure vessels”, page 17

2.13

Handling pressure vessels

Secure vessels to prevent them falling over.

Secure upright cylinders to stop them falling over and cylinders

lying flat to stop them rolling away.

Pressure vessels must never be thrown.

If dropped, the vessels could be so severely deformed that they

rupture. The refrigerant evaporates immediately, liberating con‐

siderable force. Flying fragments of cylinders can cause severe

injuries.

To protect the valves, cylinders may only be transported with the

protective cap screwed on.

Valves may break off if cylinders are not properly transported.

Never store in the vicinity of radiators.

High temperatures may occur in such areas. High temperatures

are also accompanied by high pressures and the maximum per‐

missible vessel pressure may be exceeded.

Do not heat to temperatures above 50 °C

To avoid possible risk, pressure vessel regulations specify that

vessels must not be heated to temperatures exceeding 50 °C.

Do not heat in an uncontrolled manner

Do NOT heat with a naked flame. Local overheating can cause

structural changes in the material of the vessel, which then reduce

its ability to withstand pressure. There is also a danger of refrig‐

erant decomposition due to localised overheating.

2. General information on air conditioning systems

17

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

Sealing empty vessels

Empty refrigerant vessels must always be sealed to prevent mois‐

ture from entering. Moisture can cause steel vessels to rust. This

weakens the vessel walls. In addition, any rust particles which

enter refrigeration systems from storage vessels will cause mal‐

functioning.

2.14

Safety regulations for working with ex‐

traction and charging systems

•

Before connecting the charging system to the air conditioning

system, ensure that the shut-off valves are closed.

Before disconnecting the charging system from the air condi‐

tioning system, make sure the charging process has been

completed to prevent refrigerant escaping into the atmos‐

phere.

•

Once the purified refrigerant from the charging system has

been transferred to an external compressed-gas cylinder,

close the hand shut-off valves at the cylinder and charging

system.

•

Do not expose the charging system to moisture or use it in a

wet environment.

Disconnect from power supply before performing service work

on the charging system.

An extension cable should not normally be used because it

can increase the fire hazard. If the use of an extension cable

is unavoidable, the minimum cross-section should be 2.5

2

mm .

•

In case of fire, remove external cylinder.

If any oil from the air conditioning system is drawn off by the

suction unit into the measuring container provided, it must be

subsequently transferred to a sealable container, as it con‐

tains a small quantity of refrigerant, which must not escape

into the environment.

•

Following shutdown, the air conditioner service station must

be secured to stop it rolling away.

2.15

Safety measures for working on vehi‐

cles with air conditioning system and for

handling refrigerant R134a

Vehicles with high-voltage system (hybrid vehicles)

High voltage! Danger to life!

The voltage levels in the high-voltage system constitute a safety

hazard. Danger of severe or fatal injuries from electric shock if

high-voltage components or high-voltage wiring are damaged.

– Carry out visual check of high-voltage components and high-

voltage wiring.

– Never use cutting/forming tools or other sharp-edged imple‐

ments.

– Never perform work using welding, brazing, thermal bonding

or hot air.

18

Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

Risk of injury - engine may start unexpectedly

It is difficult to determine whether the drive system of an electric

vehicle or hybrid vehicle is active. Moving parts can trap or draw

in parts of the body.

– Switch off ignition.

– Place ignition key outside vehicle.

Risk of damage to high-voltage wiring

Incorrect handling may result in damage to the insulation of high-

voltage wires or high-voltage connectors.

– Never use high-voltage wiring or high-voltage connectors as

a support.

– Never prop tools against high-voltage wiring or high-voltage

connectors.

– Never bend or kink high-voltage wiring.

– Pay attention to coding when connecting high-voltage con‐

nections.

For all work on vehicles with high-voltage system, note additional

warnings for working on such vehicles

⇒ “1 Warning instructions when working on vehicles with high-

voltage system”, page 1 .

Risk of injury if auxiliary air conditioner is activated

On electric and hybrid vehicles, the auxiliary air conditioner can

switch itself on if it has been activated. The radiator fans can start

up automatically and trap or draw in parts of the body.

– Deactivate auxiliary air conditioner.

Vehicles with start/stop system

Risk of injury - engine may start unexpectedly

The engine can start unexpectedly if the vehicle's start/stop sys‐

tem is activated. A message in the instrument cluster indicates

whether the start/stop system is activated.

– To deactivate the start/stop system, switch off the ignition.

2. General information on air conditioning systems

19

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

All vehicles

WARNING

Danger of asphyxiation, frostbite and poisoning from escaping

refrigerant

Injury risk due to escaping refrigerant

♦ Danger of asphyxiation from displacement of surrounding

air

♦ Danger of frostbite (or risk of cryogenic burns due to evap‐

oration of liquid refrigerant)

♦ Danger of poisoning from products of decomposition

Precautionary measures

•

Work may only be performed on the refrigerant circuit of

an air conditioning system in well ventilated areas.

•

Ensure good ventilation when handling refrigerant and

working on the refrigerant circuit (exchange of air at least

once per hour in workshops and 3 times per hour in low-

level areas (e.g. inspection pits). Switch on workshop

exhaust extraction system.

•

Vessels and devices containing refrigerant must only be

stored in well-ventilated areas (e.g. not in cellars or near

cellar entrances).

•

Never inhale escaping refrigerant vapour.

Wear suitable protective gloves and safety goggles when

handling refrigerant and working on the refrigerant circuit.

•

It is advisable to keep an eye bath to hand.

Work may only be performed on the refrigerant circuit of

an air conditioning system in well ventilated areas. Switch

on workshop extraction systems, if available.

•

Refrigerant must not be stored in low-level areas (e.g. cel‐

lars), including the areas around the exits and windows.

First aid

•

Anyone who accidentally inhales concentrated refrigerant

vapours must be removed from the hazard area and

placed in a lying position in the open air immediately. Keep

the person concerned warm and calm. Perform artificial

respiration in the event of breathing difficulties (administer

oxygen if necessary). If the person affected is having great

difficulty breathing or is not breathing at all, tilt back head

and administer artificial respiration. Consult a doctor.

•

Should liquid refrigerant come into contact with the eyes,

rinse them thoroughly with water for about 15 minutes.

Then administer eye drops and consult a doctor immedi‐

ately even if no pain is felt.

•

Never attempt to administer liquids through the mouth of

an unconscious person. Consult a doctor if the symptoms

persist or in any cases of doubt.

The doctor must be informed that the frostbite was caused

by refrigerant R134a. Should refrigerant come into contact

with other parts of the body even though the safety pre‐

cautions have been observed, these areas must also be

rinsed with cold or lukewarm water immediately for ap‐

prox. 15 minutes.

20

Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

•

Following accidental contact with eyes or mucous mem‐

branes, immediately rinse with copious amounts of run‐

ning water and consult an eye specialist.

In the event of skin contact, immediately remove wet cloth‐

ing and rinse the areas of skin affected with plenty of cold

or lukewarm water (never use hot water). Consult a doctor

in the event of frostbite.

Note

♦ Refrigerant has virtually no perceptible smell and therefore

cannot be noticed.

♦ Refrigerant gas is heavier than air and accumulates in low-

level areas such as inspection pits, cellars and hollows, where

it displaces the ambient air and thus the oxygen. Staying in

areas where the air has a low oxygen content is potentially

fatal.

♦ Liquid refrigerant escaping from a leak (or similar) evaporates

at an ambient pressure of approx. 1 bar at around -29℃. If the

refrigerant evaporates on the skin, it will cause frostbite or

cryogenic burns. Sensitive parts of the body such as the eyes

are particularly at risk. Large-scale cryogenic burns are po‐

tentially fatal.

♦ Refrigerant decomposes if it comes into contact with a flame

or a hot surface. Danger of poisoning if toxic products of de‐

composition are inhaled. A pungent odour indicates that prod‐

ucts of decomposition have already formed. Do NOT inhale

these substances, otherwise the respiratory tract, lungs and

other organs could be damaged.

♦ The specific hazards associated with refrigerant and the sub‐

stance data etc. can be found in the safety data sheets. Safety

data sheets for refrigerant, refrigerant oil etc. can be found in

“Audi ServiceNet.”

♦ The following procedure is an example of how to access the

“Audi ServiceNet”. Depending on the country, the procedure

may also appear in a different portal or in a different submenu.

For precise details on how to find the “Safety data sheets” in

the dealer portal, follow the instructions provided on the “Audi

Partner Portal” or on “Audi ServiceNet”.

Example of how to search for the safety data sheets in the “Audi

ServiceNet” ⇒ table

– Select path:

Audi ServiceNet

Handbooks

HSO

Environmental protection

Safety data sheets

Safety data sheets and operating instruc‐

tions

– Select the range criteria.

– Enter the data on the material master (e.g. the part number or

trade name).

Welding, brazing and soldering work must not be performed on

components of air conditioning system when charged. This also

applies to welding and soldering work on the vehicle if there is a

2. General information on air conditioning systems

21

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

danger of air conditioner components becoming hot. When per‐

forming paintwork repairs, the temperature in the drying booth or

preheating zone must not exceed 80 °C.

Reason:

Exposure to heat generates considerable pressure in the system,

which could cause the high-pressure safety valve to open.

Remedy:

– Discharge refrigerant circuit using air conditioner service sta‐

tion.

Note

Damaged or leaking components of the air conditioning system

must not be repaired by welding or soldering. They must always

be renewed.

Refrigerant vessels (e.g. charging cylinders of air conditioner

service station) must never be subjected to excessive heat or ex‐

posed to direct sunlight.

Remedy:

– Vessels must never be completely filled with liquid refrigerant.

Without sufficient room for expansion (gas cushion), vessels

will rupture with explosive effect in the event of an increase in

temperature ⇒ page 11 .

Refrigerant must NOT be transferred to systems or containers in

which air is present.

Remedy:

– Evacuate systems and containers before charging with refrig‐

erant.

2.16

Basic rules for working on refrigerant cir‐

cuit

Vehicles with high-voltage system (hybrid vehicles)

High voltage! Danger to life!

The voltage levels in the high-voltage system constitute a safety

hazard. Danger of severe or fatal injuries from electric shock.

– Persons with life-sustaining or other electronic medical devi‐

ces in or on their body must not perform any work on the high-

voltage system. Such medical devices include internal anal‐

gesic pumps, implanted defibrillators, pacemakers, insulin

pumps and hearing aids.

– The high-voltage system must be de-energised by a suitably

qualified person.

Risk of injury - engine may start unexpectedly

It is difficult to determine whether the drive system of an electric

vehicle or hybrid vehicle is active. Moving parts can trap or draw

in parts of the body.

– Switch off ignition.

– Place ignition key outside vehicle.

22

Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

Risk of damage to high-voltage wiring

Incorrect handling may result in damage to the insulation of high-

voltage wires or high-voltage connectors.

– Never use high-voltage wiring or high-voltage connectors as

a support.

– Never prop tools against high-voltage wiring or high-voltage

connectors.

– Never bend or kink high-voltage wiring.

– Pay attention to coding when connecting high-voltage con‐

nections.

For all work on vehicles with high-voltage system, note additional

warnings for working on such vehicles

⇒ “1 Warning instructions when working on vehicles with high-

voltage system”, page 1 .

If work near high-voltage system components is necessary, per‐

form a visual check of the high-voltage components and wires to

check for damage ⇒ page 2 .

If work on high-voltage system components is necessary, de-en‐

ergise high-voltage system ⇒ Rep. gr. 93 ; De-energising high-

voltage system .

Vehicles with start/stop system

Risk of injury - engine may start unexpectedly

The engine can start unexpectedly if the vehicle's start/stop sys‐

tem is activated. A message in the instrument cluster indicates

whether the start/stop system is activated.

– To deactivate the start/stop system, switch off the ignition.

All vehicles

♦ General notes ⇒ page 24

♦ Cleaning refrigerant circuit ⇒ page 24

♦ Additionally for vehicles with air conditioner compressor with

no magnetic clutch (with air conditioner compressor regulating

valve - N280- ) ⇒ page 25

♦ O-rings ⇒ page 27

2. General information on air conditioning systems

23

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

⇒ “2.16.1 General notes”, page 24

⇒ “2.16.2 Cleaning refrigerant circuit”, page 24

⇒ “2.16.3 Additionally for vehicles with air conditioner compressor

without magnetic clutch (with air conditioner compressor regulat‐

ing valve N280 only)”, page 25

⇒ “2.16.4 Additional information on vehicles with high-voltage

system”, page 25

⇒ “2.16.5 O-rings”, page 27

2.16.1

General notes

•

Observe specific instructions relating to workplaces ⇒ Audi

ServiceNet, HSO Environmental Protection .

•

Ensure absolute cleanliness when working.

Wear safety goggles and gloves when working with refrigerant

and nitrogen.

•

Switch on the available workshop exhaust extraction systems.

Always use air conditioner service station to discharge refrig‐

erant circuit, then unfasten screw connections and renew

defective components.

•

Use caps to seal off opened components and hoses to prevent

moisture and dirt from entering the system.

•

Use only tools and materials intended for refrigerant R134a.

Seal opened refrigerant oil containers to guard against mois‐

ture.

Note

♦ After completing service work, screw sealing caps (with seals)

onto service connections and all connections with valves.

♦ Before starting up air conditioning system, check specified ca‐

pacity for vehicle ⇒ page 292 .

♦ Do not top up refrigerant in circuit; discharge existing refriger‐

ant and re-charge system.

2.16.2

Cleaning refrigerant circuit

The refrigerant circuit must be cleaned (flushed) with refrigerant

R134a ⇒ page 100 (or blown out with compressed air and nitro‐

gen ⇒ page 95 ) in the following cases:

– If moisture or dirt has entered the refrigerant circuit (e.g. fol‐

lowing an accident)

– If the refrigerant oil is dark and viscous

– If there is too much refrigerant oil in the refrigerant circuit after

renewing compressor

– If the air conditioner compressor has to be renewed due to

“internal” damage (e.g. noise or no output)

Note

When blowing out components with compressed air and nitrogen,

always extract the gas mixture escaping from the components

with suitable extraction units (workshop extraction system).

24

Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

2.16.3

Additionally for vehicles with air condi‐

tioner compressor without magnetic

clutch (with air conditioner compressor

regulating valve - N280- only)

•

Only start the engine after the refrigerant circuit has been as‐

sembled completely (constant air conditioner compressor op‐

eration).

If the engine has to be operated with the refrigerant circuit

empty, only do so for as long as absolutely essential and avoid

increased engine speeds.

2.16.4

Additional information on vehicles with

high-voltage system

Vehicles with high-voltage system (hybrid vehicles)

High voltage! Danger to life!

The voltage levels in the high-voltage system constitute a safety

hazard. Danger of severe or fatal injuries from electric shock if

high-voltage components or high-voltage wiring are damaged.

– Carry out visual check of high-voltage components and high-

voltage wiring.

– Never use cutting/forming tools or other sharp-edged imple‐

ments.

– Never perform work using welding, brazing, thermal bonding

or hot air.

Risk of injury - engine may start unexpectedly

It is difficult to determine whether the drive system of an electric

vehicle or hybrid vehicle is active. Moving parts can trap or draw

in parts of the body.

– Switch off ignition.

– Place ignition key outside vehicle.

Risk of damage to high-voltage wiring

Incorrect handling may result in damage to the insulation of high-

voltage wires or high-voltage connectors.

– Never use high-voltage wiring or high-voltage connectors as

a support.

– Never prop tools against high-voltage wiring or high-voltage

connectors.

– Never bend or kink high-voltage wiring.

– Pay attention to coding when connecting high-voltage con‐

nections.

♦ For all work on vehicles with high-voltage system, note addi‐

tional warnings for working on such vehicles

2. General information on air conditioning systems

25

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

⇒ “1 Warning instructions when working on vehicles with high-

voltage system”, page 1 .

♦ If work is necessary in the vicinity of high-voltage system com‐

ponents, perform a visual inspection of the high-voltage com‐

ponents and wiring to check for damage ⇒ page 2 and note ⇒

Rep. gr. 00 ; Safety precautions or ⇒ Electrical system; Rep.

gr. 93 ; General warning instructions for work on the high-

voltage system .

♦ For further information on the high-voltage system, refer to ⇒

Rep. gr. 00 ; Safety precautions or ⇒ Electrical system; Rep.

gr. 93 ; General warning instructions for work on the high-

voltage system .

♦ If work on high-voltage system components is necessary, de-

energise high-voltage system ⇒ Rep. gr. 00 ; Safety precau‐

tions or ⇒ Electrical system; Rep. gr. 93 ; General warning

instructions for work on the high-voltage system .

•

The engine should only be started after the refrigerant circuit

has been assembled completely.

•

On vehicles with battery cooling, hybrid operation is only pos‐

sible with the air conditioner charged and with no air condi‐

tioner faults stored ⇒ Vehicle diagnostic tester in “Guided

Fault Finding” mode for air conditioner and battery regulation

•

After installing the electrically driven air conditioner compres‐

sor and then charging the refrigerant circuit, first start up the

compressor via the “Compressor run-in” function of the basic

setting routine. Otherwise, the air conditioner compressor may

be damaged if refrigerant oil has accumulated in the compres‐

sion chamber of the air conditioner compressor due to inap‐

propriate storage prior to installation. ⇒ Vehicle diagnostic

tester, “Guided Fault Finding” function for air conditioner and

battery regulation

•

An electrically driven air conditioner compressor may only be

activated when the refrigerant circuit is charged. Running the

air conditioner compressor with the refrigerant circuit empty

could lead to compressor damage ⇒ Vehicle diagnostic tester

(“Guided Fault Finding” mode for air conditioner and battery

regulation) .

Before the refrigerant circuit can be discharged, evacuated

and charged, specific electrically operated valves (may vary

depending on the refrigerant circuit layout) must be opened

(e.g. on the Audi Q7 e-tron) ⇒ Heating, air conditioning; Rep.

gr. 87 ; Refrigerant circuit and ⇒ Vehicle diagnostic tester in

“Guided Fault Finding” mode.

•

To check whether the air conditioner is functioning properly,

specific electrically operated valves must be opened or closed

(e.g. on the Audi Q7 e-tron) ⇒ Heating, air conditioning; Rep.

gr. 87 ; Refrigerant circuit and ⇒ Vehicle diagnostic tester in

“Guided Fault Finding” mode.

Depending on the vehicle, high pressure may not be available

at the service connection on the high-pressure side in all air

conditioner operating modes (e.g. on the Audi Q7 e-tron). The

senders installed in the refrigerant circuit must therefore be

used to check that the air conditioner in these vehicles is func‐

tioning properly ⇒ Heating, air conditioning; Rep. gr. 87 ;

Refrigerant circuit and ⇒ Vehicle diagnostic tester in “Guided

Fault Finding” mode.

– To minimise the number of automatic engine starts when the

vehicle's drive system is active during test and measurement

work, charge the vehicle batteries e.g. with the battery

charger 60A - VAS 5904- in battery standby mode ⇒ Electrical

system; General information; Rep. gr. 27 ; Charging battery

26

Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

and ⇒ Electrical system; Rep. gr. 93 ; General warning in‐

structions for work on the high-voltage system .

– For test and measurement work that requires the vehicle's

drive system to be active (READY) or the ignition to be switch‐

ed on, move the selector lever to position “P”, activate the

parking brake and take care to keep well clear of the engine

when it is running. Set up any tools needed so that they cannot

come into contact with moving parts.

2.16.5

O-rings

♦ Use only seals which are resistant to refrigerant R134a and

the corresponding refrigerant oils. Colour coding of O-ring

seals is no longer employed. Black and coloured O-rings are

used.

♦ Note the correct inside diameter of the seals used ⇒ Electronic

parts catalogue , ⇒ Heating, air conditioning; Rep. gr. 87 ;

Refrigerant circuit (vehicle-specific Workshop Manual).

♦ Seals may only be used once.

♦ Before fitting, lightly lubricate seals with refrigerant oil (PAG

oil).

2.17

Before using air conditioner after system

has been re-charged

Mechanically driven air conditioner compressor

After air conditioner compressor is attached to engine (before belt

is fitted or drive shaft is installed)

⇒ “5.3.6 Starting up air conditioner after charging”, page 92 and

⇒ Heating, air conditioning; Rep. gr. 87 ; Air conditioner com‐

pressor .

– Rotate air conditioner compressor about 10 revolutions by

hand using the magnetic clutch pulley or belt pulley.

After re-charging

⇒ “5.3.6 Starting up air conditioner after charging”, page 92

– Start engine with air conditioner switched off ( air conditioning

system magnetic clutch - N25- and air conditioner compressor

regulating valve - N280- are not activated).

– When engine idling speed has stabilised, switch on air condi‐

tioner compressor and run it for at least 10 minutes at idling

speed with maximum cooling output.

Electrically driven air conditioner compressor

– After charging the refrigerant circuit, start the electrically driv‐

en air conditioner compressor first using the “Compressor run-

in” function of the basic setting

⇒ “5.3.6 Starting up air conditioner after charging”,

page 92 and ⇒ Vehicle diagnostic tester, “Guided Fault

Finding” function for air conditioner and battery regulation

2. General information on air conditioning systems

27

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General information on air conditioning systems for Your Audi A2 SUV 1999-2005

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