Get Technical data Basic technical and physical properties Guide for Volkswagen Sharan VAN Second Generation (2010-2023)

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Air conditioning systems with refrigeranR1234yf - General information - Edition 07.2017

6

Basic technical and physical proper‐

ties

⇒ “6.1 Basics of air conditioning technology”, page 16

⇒ “6.2 Physical properties”, page 19

⇒ “6.3 Produccharacteristics”, page 26

⇒ “6.4 Function and role of air conditioning system”, page 26

⇒ “6.5 Other reference material”, page 28

6.1

Basics of air conditioning technology

⇒ “6.1.1 Physical properties of air conditioning system”,

lk

page 16

⇒ “6.1.2 Pressure and boiling poinof refrigerant”, page 17

⇒ “6.1.3 Vapour pressure table for refrigerant”, page 17

⇒ “6.2 Physical properties”, page 19

6.1.1

Physical properties of air conditioning

system

The 4 familiar states of water apply to air conditioning refrigerants

as well.

1 - Gas (invisible)

2 - Vapour

3 - Liquid

4 - Solid

When water is heated in a vessel (heaabsorption), water vapour

can be seen to rise. If the vapour is heated by further heaab‐

sorption, the visible vapour becomes invisible gas. The process

is reversible. If heais extracted from gaseous water -A-, i

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

A - Heaabsorption

B - Headissipation

Heaalways flows from a warmer to a colder substance

Every substance consists of a mass of moving molecules. The

fasmoving 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

thaof the colder substance is accelerated. This continues until

the molecules in both materials are moving athe same speed.

They are then athe same temperature and no further heaex‐

change takes place.

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6.1.2

Pressure and boiling poinof refrigeran

The boiling poingiven in tables for a liquid is always referenced

to atmospheric pressure (1 bar absolute pressure). If the pressure

over a fluid changes, its boiling poinchanges as well.

Note

lk

Pressure is indicated in various units: 1 MPa (Mega-Pascal) is

equal to 10 bar or 145 psi; 1 bar absolute pressure is equal to

0 bar, which is abouthe same as ambienpressure (atmospheric

pressure).

Iis well known thae.g. the lower the pressure, the lower the

temperature awhich water boils.

The vapour pressure curves for water and for R1234yf refrigeran

show thaaconstanpressure and falling temperature the vapour

becomes liquid (in the condenser), and thawhen pressure drops,

for example, the refrigeranchanges from liquid into the vaporous

state (in the evaporator).

Vapour curve, water

A - Liquid

B - Gaseous

C - Vapour curve, water

1 - Pressure on the liquid in bar (absolute)

2 - Temperature in °C

Vapour pressure curve for refrigeranR1234yf

A - Liquid

B - Gaseous

D - Vapour pressure curve for refrigeranR1234yf

1 - Pressure on the liquid in bar (absolute)

2 - Temperature in °C

Note

The vapour pressure curves of both refrigerants, R1234yf and

R134a, are very similar across a broad temperature range. The

pressure difference between the two refrigerants in a temperature

range of 0 C to +50°C is only abou0.2 bar, for example, which

is why iis nopossible to differentiate between the two refriger‐

ants ⇒ “6.1.3 Vapour pressure table for refrigerant”, page 17

and ⇒ Air conditioning system with R134a refrigerant; Rep. gr.

87 ; General information abouthe air conditioning system and

refrigerancircui. Iis only possible to determine a difference

using relevansensors, which can analyse the chemical structure

of the refrigeran

⇒ “6.2.16 Analysis of refrigeranR1234yf”, page 24 .

6.1.3

Vapour pressure table for refrigeran

The vapour pressure table for every refrigeranis published in

literature for refrigeration system engineers. This table makes i

6. Basic technical and physical properties

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Air conditioning systems with refrigeranR1234yf - General information - Edition 07.2017

possible to determine the vapour pressure acting on the column

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

Since its own characteristic vapour pressure table is known for

each refrigerant, iis possible to establish the type of refrigeran

by measuring the pressure and temperature of refrigerants whose

vapour pressure changes over a certain temperature range (does

noapply when differentiating between R1234yf and R134a as

the vapour pressures are too close

⇒ “6.1.2 Pressure and boiling poinof refrigerant”, page 17 ).

Note

♦ The means of differentiation are only given for pure refriger‐

ants whose vapour pressures differ sufficiently. If differen

refrigerants are mixed for form a new refrigeran(e.g. 3 differ‐

enrefrigerants to form R407C refrigerant), a vapour pressure

will be created in accordance with the vapour pressures of the

individual refrigerants and their percentage in the mixture.

♦ Absolute pressure means tha“0 bar” corresponds to an ab‐

solute vacuum. The normal ambienpressure corresponds to

“1 bar” absolute pressure. On mospressure gauges, a read‐

ing of “0 bar” corresponds to an absolute pressure of one bar

(which is confirmed by the existence of a “-1 bar” marking be‐

neath the “0” scale marking).

♦ Pressure is indicated in various units: 1 MPa (Mega-Pascal)

is equal to 10 bar or 145 psi; 1 bar absolute pressure is equal

to 0 bar, which is abouthe same as ambienpressure (at‐

mospheric pressure).

♦ The vapour pressures of the two refrigerants, R1234yf and

R134a, are very similar across a broad temperature range,

which is why no difference can be established between them

⇒ Air conditioning system with R134a refrigerant, General in‐

formation abouthe air conditioning system . Iis only possible

lk

to determine a difference using relevansensors, which can

analyse the chemical structure of the refrigeran

⇒ “6.2.16 Analysis of refrigeranR1234yf”, page 24 .

Temperature in °C

Pressure in bar (positive pres‐

sure) R1234yf

-40

-30

-25

-20

-15

-10

-5

-0.40

-0.01

0.12

0.50

0.83

1.21

1.65

2.15

2.72

3.36

4.09

4.90

5.81

6.82

7.93

9.17

10.52

0

5

10

15

20

25

30

35

40

45

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Air conditioning systems with refrigeranR1234yf - General information - Edition 07.2017

Temperature in °C

Pressure in bar (positive pres‐

sure) R1234yf

50

55

60

65

70

75

80

85

90

12.01

13.64

15.41

17.35

19.46

21.75

24.24

26.94

29.09

6.2

Physical properties

⇒ “6.2.1 R1234yf refrigerant”, page 19

⇒ “6.2.2 Potential risks with R1234yf refrigerant”, page 20

⇒ “6.2.3 Physical and chemical properties of R1234yf refrigerant”,

page 20

lk

⇒ “6.2.4 Critical point”, page 20

⇒ “6.2.5 Environmental aspects of refrigeranR1234yf”,

page 21

⇒ “6.2.6 Trade names and designations of R1234yf refrigerant”,

page 21

⇒ “6.2.7 Colour and odour of R1234yf refrigerant”, page 22

⇒ “6.2.8 Vapour pressure of R1234yf refrigerant”, page 22

⇒ “6.2.9 Physical properties of R1234yf refrigerant”, page 22

⇒ “6.2.10 How R1234yf refrigeranreacts to metals and plastics”,

page 22

⇒ “6.2.11 Critical temperature / critical pressure of R1234yf re‐

frigerant”, page 23

⇒ “6.2.12 Water contenof R1234yf refrigerant”, page 23

⇒ “6.2.13 Flammability / decomposition of R1234yf refrigerant”,

page 23

⇒ “6.2.14 Charge factor of refrigeranR1234yf”, page 23

⇒ “6.2.15 Evidence of leaks in a refrigerancircuiwith R1234yf

refrigerant”, page 24

⇒ “6.2.16 Analysis of refrigeranR1234yf”, page 24

⇒ “6.2.17 Returning contaminated R1234yf refrigeranfor analy‐

sis, processing or disposal”, page 25

6.2.1

R1234yf refrigeran

♦ Air conditioners in vehicles employ the evaporation and con‐

densation process. A substance (the refrigerant) is moved

aboua circuiwithin an enclosed system.

♦ The substance is one thahas a low boiling point, in this in‐

stance R1234yf refrigerant.

♦ The R1234yf refrigeranis marketed under various names

(e.g. HFO 1234yf, Opteon 1234yf etc.).

6. Basic technical and physical properties

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lk

♦ For the air conditioning system, only approved refrigeranwith

the requisite level of purity may be used

⇒ “6.2.16 Analysis of refrigeranR1234yf”, page 24 .

♦ R1234yf refrigeranis a halogenated hydrocarbon compound

with the chemical designation “2,3,3,3-tetrafluoroprop-1-ene”

which boils a-29.4°C aa vapour pressure of “1 bar” (equiv‐

alento ambienpressure).

6.2.2

Potential risks with R1234yf refrigeran

♦ The refrigeranis flammable with ambienair in a certain mix‐

ture ratio

⇒ “6.2.3 Physical and chemical properties of R1234yf refrig‐

erant”, page 20 and

⇒ “6.2.13 Flammability / decomposition of R1234yf refriger‐

ant”, page 23 .

♦ Rapid vaporisation of the liquid can cause freezing injuries

♦ High vapour concentrations can cause headaches, dizziness,

drowsiness and nausea and even loss of consciousness.

6.2.3

Physical and chemical properties of

R1234yf refrigeran

The following is a lisof the main properties and safety information

for R1234yf refrigerant. The complete details can be found in the

respective safety data sheets on the ⇒ VW / Audi ServiceNe.

Chemical formula

CF3CF=CH2

Chemical designation

2,3,3,3-tetrafluoroprop-1-ene,

HFO-1234yf

Boiling poina1 bar

Solidification poin

Critical temperature

Critical pressure

-29.4 °C

-152.2 °C

94.7 °C

32.82 bar (positive pressure)

33.82 bar (absolute pressure)

Self-combustion temperature 405°C a1.02 bar (absolute

pressure)

Flammability

Flammable gas

♦ Lower explosion threshold

6.2% (volume)

♦ Upper explosion threshold

12.3% (volume)

Form

Colour

Odour

Compressed, liquefied gas

Colourless

Weak odour

6.2.4

Critical poin

The critical poin(critical temperature and critical pressure)

means the poinabove which there is no longer a surface of sep‐

aration between liquid and gas.

A substance above its critical poinis always in the gaseous state.

Atemperatures below the critical point, all types of refrigeran

contained within a pressure vessel exhibia liquid phase and a

gas phase, i.e. there is a gas cushion above the liquid.

As long as there is gas in the pressure vessel alongside the liquid,

the pressure depends directly on the ambientemperature

⇒ “6.1.3 Vapour pressure table for refrigerant”, page 17 .

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Air conditioning systems with refrigeranR1234yf - General information - Edition 07.2017

Note

♦ Refrigerants used in motor vehicles musnobe mixed to‐

her. Only the refrigeranprescribed for the respective air

conditioning system may be used.

♦ The vapour pressures of the two refrigerants, R1234yf and

R134a, are very similar across a broad temperature range,

which is why no difference can be established between them

⇒ Air conditioning system with R134a refrigerant, General in‐

formation abouthe air conditioning system . Iis only possible_lk

to determine a difference using relevansensors, which can

analyse the chemical structure of the refrigeran

⇒ “6.2.16 Analysis of refrigeranR1234yf”, page 24 .

6.2.5

Environmental aspects of refrigeran

R1234yf

♦ R1234yf is a fluorocarbon (FC) and contains no chlorine.

♦ R1234yf has a shorter atmospheric life than R12 and R134a

refrigeranand therefore has a less significangreenhouse ef‐

fec(lower global warming potential).

♦ R1234yf does nodamage the ozone layer, the potential to

reduce the amounof ozone is zero (as is the case with

R134a).

♦ The global warming potential (GWP) of R1234yf is 4 (the GWP

for carbon dioxide is 1).

♦ The contribution of R1234yf towards global warming is lower

than the R134a refrigeranby a factor of “350” (GWP of R134a

is abou1400).

Note

♦ The global warming effecof substances is calculated accord‐

ing to various methods based on their effecover a period of

100 years, which is why the results differ (e.g. R134a has a

GWP between 1300 and 1450).

♦ In order to compare the impacof various greenhouse gases

on the earth atmosphere, a calculation is carried ouusing the

carbon dioxide equivalent. The refrigeranR1234yf has a

GWP of 4, i.e. 1 kg of this refrigeranhas the same impacon

the earth atmosphere as 4 kg of carbon dioxide (“CO ”).

2

6.2.6

Trade names and designations of

R1234yf refrigeran

RefrigeranR1234yf is currently available under the following

trade names:

♦ H-FKW 1234yf

♦ HFO 1234yf

♦ “Opteon yf” or“ Solstice yf” (examples of company names)

6. Basic technical and physical properties

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Note

♦ Differentrade 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 names Frigen and Freon

are trade names. These also apply to refrigerants which are

noto be used in vehicles.

6.2.7

Colour and odour of R1234yf refrigeran

♦ Like water, refrigerants are colourless in both vapour and liq‐

uid form. Gas is invisible. Only the boundary layer between

gas and liquid is visible (liquid level in indicator tube of charg‐

ing cylinder or bubbles in sighglass). Liquid refrigeran

R1234yf may have a coloured (milky) appearance in a sigh

glass. This cloudiness is caused by partially dissolved refrig‐

eranoil and does noindicate a fault.

♦ Refrigerant is almosodourless. Should R1234yf refrigeran

escape, imay be possible to deteca slighsmell of ether

depending on the ambienconditions.

6.2.8

Vapour pressure of R1234yf refrigeran

In an enclosed container thais nocompletely full, refrigeran

evaporates athe surface in a quantity sufficiento form an equi‐

librium between vapour and liquid. This state of equilibrium occurs

under the influence of pressure and is often called vapour pres‐

sure. The vapour pressure is temperature-dependan

⇒ “6.1.3 Vapour pressure table for refrigerant”, page 17 .

6.2.9

Physical properties of R1234yf refriger‐

an

♦ The vapour pressure curves of the two refrigerants, R1234yf

and R134a, are very similar across a broad temperature

range, which is why no difference can be established between

them

⇒ “6.1.3 Vapour pressure table for refrigerant”, page 17 and

⇒ Air conditioning system with R134a refrigerant, General in‐

formation abouthe air conditioning system . Iis only possible

to determine a difference using relevansensors, which can

analyse the chemical structure of the refrigeran

⇒ “6.2.16 Analysis of refrigeranR1234yf”, page 24 .

♦ Lubrication of the air conditioner compressor with R1234yf is

by special synthetic refrigeranoils, e.g. PAG oils (polyalky‐

lene glycol oils) with certain additives adapted to the R1234yf

refrigeranoil, the air conditioner compressor and the operat‐

ing conditions.

6.2.10

How R1234yf refrigeranreacts to met‐

als and plastics

♦ In its pure state, R1234yf refrigeranis chemically stable and

has no corrosive effecon e.g. iron, aluminium and specially

developed plastics thaare suitable for this purpose.

♦ Contaminants in the refrigerant, however, cause components

of the refrigerancircuito become corroded and damaged

beyond repair.

♦ Unsuitable materials (e.g. seals and hoses thawere node‐

veloped for the R1234yf refrigeranand the associated refrig‐

eranoil) can also be corroded and damaged by pure R1234yf

refrigeranand refrigeranoil.

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♦ If the refrigeranis contaminated, e.g. with chlorine com‐

pounds or by the influence of UV light, metals and also plastics

developed and tested for this refrigeranand refrigeranoil can

be corroded. This can lead to blockages, leaks and deposits

on the air conditioner compressor piston.

lk

♦ Certain metals can be corroded by R1234yf refrigeran(e.g.

finely distributed aluminium, zinc, magnesium)

6.2.11

Critical temperature / critical pressure of

R1234yf refrigeran

Up to a gas pressure of 32.82 bar (which is equivalento a tem‐

perature of 94.7°C), refrigeranevaporates athe surface in a

quantity that, combined with particles of vapour, returns ito liquid

again. Above this temperature / pressure there is no longer a sur‐

face separating the liquid and gas.

6.2.12

Water contenof R1234yf refrigeran

♦ Only very small amounts of water are soluble in liquid refrig‐

erant. On the other hand, refrigeranvapour and water vapour

mix in any ratio.

♦ Any water in the refrigerancircuiwill be entrained in drople

form once the dryer in the receiver or reservoir is full (once i

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 no longer provides cooling.

♦ If the existing water athe regulating valve of the air conditioner

compressor turns to ice, a variety of complaints may be made

depending on the design of the air conditioner compressor

(either the air conditioning system stops cooling or the air con‐

ditioning system cools to such a degree thathe evaporator

ices over).

♦ Water destroys the air conditioner because ahigh pressures

and temperatures ican combine with other impurities to form

acids.

6.2.13

Flammability / decomposition of

R1234yf refrigeran

♦ In certain concentrations in the ambienair, R1234yf refriger‐

anis flammable.

♦ R1234yf begins to decompose when exposed to flames and

glowing or hosurfaces. Even UV lighcauses refrigeranto

break up (UV lighis parof normal sunlight, iis also encoun‐

tered e.g. during electrical welding), which releases poisonous

fission products thamusnobe inhaled. However, these

chemicals irritate the mucous membranes, giving adequate

warning of their presence.

♦ During decomposition, certain hazardous products such as

carbon monoxide, hydrogen fluoride and / or hydrogen halide

can be released.

6.2.14

Charge factor of refrigeranR1234yf

♦ When charging compressed gas containers (returnable cylin‐

ders, recycling cylinders etc.), observe the applicable regula‐

tions, technical rules and legislation.

♦ Never overcharge compressed gas containers (returnable cyl‐

inders, recycling cylinders etc.). The gas cushion (expansion

space) of overcharged compressed gas containers is too

small to accommodate expansion of the fluid caused by a rise

in temperature. Risk of bursting.

6. Basic technical and physical properties

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♦ To ensure safety, only use compressed gas containers fitted

with a safety valve.

♦ Returnable and recycling cylinders musbe weighed on suit‐

able scales during charging, or a method of charging by vol‐

ume musbe employed to ensure thathe permissible weigh

of the filling specified on the tank/container is noexceeded.

The maximum permissible filling volume is 80% of the maxi‐

mum refrigeranvolume of the filling weighspecified on the

returnable and recycling cylinder or 70% of the maximum filling

volume (charge factor, the smaller of the values always ap‐

plies respectively). Reason: There is no way of absolutely

lk

ruling ourefrigeranoil being filled into the returnable and re‐

cycling cylinder along with the refrigerant.

♦ There musbe space both for liquid and vapour in a container.

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

space becomes smaller. Aa certain point, there will only be

liquid in the vessel. Beyond this, even a slighincrease in tem‐

perature causes greapressure to build up in the vessel as the

liquid attempts to continue expanding despite the absence of

the necessary space. The resultanforce is sufficiento rup‐

ture the vessel. To prevencontainers from being over‐

charged, regulations governing the storage of compressed

gases specify how many kilograms may be charged into a

container for every litre of container volume. This charge factor

multiplied by the internal volume gives the permissible charge

quantity. The charge factor for refrigeranused in vehicles is

1.15 kg/litre.

♦ Since contaminated refrigerancould have a differendensity

than pure R1234yf refrigerant, the maximum permissible

charge factor musalways be observed.

6.2.15

Evidence of leaks in a refrigerancircui

with R1234yf refrigeran

♦ The refrigerancircuicould develop leaks, for example, from

the use of unsuitable or contaminated refrigeranor untested

materials in unsuitable components.

♦ Since a small leak will involve only small quantities of refrig‐

erant, evidence of leaks should be soughusing an electronic

leak detector or by introducing a leak detection additive to the

refrigerancircuit. Electronic leak detectors can detecleakage

rates of less than 5 grams loss of refrigeranper year.

Note

Use mushowever be made of leak detectors designed for the

composition of the respective refrigerant. For example, leak de‐

tectors for R12 refrigeranare nosuitable for R1234yf refrigeran

as these leak detectors do noalways respond. Even leak detec‐

tors thaare designed jusfor R134a refrigeranare nosuitable

for R1234yf refrigeranbecause R1234yf refrigeranhas a differ‐

enchemical structure than R134a. Subsequently, these leak

detectors only respond to high concentrations of refrigeranin the

air or noaall ⇒ Electronic parts catalogue .

6.2.16

Analysis of refrigeranR1234yf

For operation of the air conditioning system, iis importantha

the refrigeranused has a certain degree of purity.

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Note

♦ A faulty gas analysis is possible from air in the refrigeranho‐

ses or non-observance of the procedure for gas analysis as

detailed in the operating instructions.

♦ Carefully follow the operating instructions of the gas analysis

device / air conditioner service station .

♦ Evacuate refrigeranhoses of the air conditioner service sta‐

tion before connecting the service couplings to the refrigeran

circui/ gas cylinder with R1234yf refrigeranhose (see oper‐

ating instructions of gas analysis device / air conditioner serv‐

ice station

⇒ “2.3 Performing gas analysis of refrigerant”, page 134 .

Contamination with other refrigerants or gases can cause dam‐

age and thereby failure of the air conditioning system and air

conditioner service station .

Contaminated refrigeranmusbe analysed and then processed

(or disposed of) as gas of unknown composition in accordance

with the relevanlegal requirements

⇒ “2.3 Performing gas analysis of refrigerant”, page 134 .

Note

lk

Return contaminated R1234yf refrigeranto your refrigeransup‐

plier for analysis. If, owing to refrigerancircuidamage thahas

already occurred or is expected, iis necessary for you to know

exactly which impurities the refrigeranis contaminated with, sub‐

mian application and requesanalysis results

⇒ “6.2.17 Returning contaminated R1234yf refrigeranfor analy‐

sis, processing or disposal”, page 25 .

The following thresholds apply for clean R1234yf refrigerandur‐

ing the gas analysis:

♦ The extracted refrigerangas consists of aleas95% R1234yf

refrigerant.

♦ The percentage of impurities (oxygen, nitrogen, vapour, other

refrigerants) is less than 5%.

Note

To prevenliquid components (e.g. droplets of refrigeranoil) in

the extracted refrigerangas from falsifying the resulof the gas

analysis, separators (filters) are installed in the gas analysis de‐

vice thaseparate these droplets of liquid. Renew filters in ac‐

cordance with the specifications in the operating instructions

accompanying the gas analysis device and air conditioner service

station ⇒ Operating instructions of gas analysis device or ⇒ Op‐

erating instructions of air conditioner service station .

6.2.17

Returning contaminated R1234yf refrig‐

eranfor analysis, processing or dispos‐

al

♦ When returning contaminated refrigeranfor analysis, pro‐

cessing/recycling or disposing of refrigeranthais no longer

usable, the legal requirements musbe observed

⇒ “2 Legal texts and regulations”, page 5 and ⇒ VW / Audi

ServiceNe.

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♦ When disposing of refrigeranoil thais no longer usable, the

legal requirements musbe observed

⇒ “2 Legal texts and regulations”, page 5 and ⇒ VW / Audi

ServiceNe.

♦ To protecthe environment, no refrigeranshould be released

into the atmosphere

⇒ “2 Legal texts and regulations”, page 5 .

♦ If, during the gas analysis, iis found thathe R1234yf refrig‐

eranis contaminated with a differengas, imusbe extracted

from the refrigerancircuiand returned to your gas supplier to

be analysed, processed or disposed of as gas of unknown

composition in accordance with the legal requirements ⇒ VW /

Audi ServiceNeand

⇒ “2.13 Filling contaminated refrigeranin a recycling cylinder

for analysis, processing or disposal”, page 161 .

Note

Return contaminated R1234yf refrigeranto ^ly^kour refrigeransup‐

plier for analysis. If, owing to refrigerancircuidamage thahas

already occurred or is expected, iis necessary for you to know

exactly which impurities the refrigeranis contaminated with, sub‐

mian application by requesting analysis results

⇒ “2.4 Emptying refrigerancircuit”, page 137 .

6.3

Produccharacteristics

R1234yf refrigeranused in motor vehicle air conditioning sys‐

tems belongs to the new generation of refrigerants based on

chlorine-free, partially fluorinated hydrocarbons.

With regard to their physical properties, these are refrigerants

which have been liquefied under pressure. These are subjecto

the regulations governing pressure vessels and use is only to be

made of approved and appropriately marked containers.

Compliance with specific conditions is required to ensure safe and

proper use ⇒ “1 Safety information”, page 1 .

6.4

Function and role of air conditioning sys‐

tem

⇒ “6.4.1 Principle of operation”, page 26

⇒ “6.4.2 Comfort”, page 27

⇒ “6.4.3 Environmental aspects”, page 27

6.4.1

Principle of operation

♦ The temperature in the passenger compartmendepends on

the amounof hearadiated through the windows and con‐

ducted by the metal parts of the body. In order to maintain

comfortable temperatures for the occupants on very warm

days, parof the prevailing heamusbe pumped away.

♦ Since heaspreads towards cooler bodies, a unithacan cre‐

ate low temperatures is fitted in the vehicle interior. Within this,

refrigeranis continually evaporated. The hearequired to do

this is extracted from the air flowing through the evaporator.

♦ The refrigerancarries the heawith ias iis pumped away by

the air conditioner compressor. The work performed by the air

conditioner compressor on the refrigeranincreases its hea

contenand its temperature. This is now substantially higher

than thaof the surrounding air.

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♦ The horefrigeranflows with its heacontento the condenser.

Here, the refrigerandissipates its heato the surrounding air

via the condenser due to the temperature gradienbetween

the refrigeranand the surrounding air.

♦ The refrigeranthus acts as a heatransfer medium. As iis to

be re-used, the refrigeranis returned to the evaporator.

♦ For this reason all air conditioning systems are based on the

refrigerancirculation principle. There are however differences

in the composition of the units

⇒ “1.1 System overview - refrigerancircuit”, page 30 .

6.4.2

Comfor

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♦ A basic requiremenfor concentration and safe driving is a

feeling of comforin the passenger compartment. This comfor

is only reached by using an air conditioning system, particu‐

larly when iis hoand humid. Of course, open windows, an

open sunroof or increased air ventilation can contribute to

comfort, buthey all have certain disadvantages within the ve‐

hicle interior, such as additional noise, draughts, exhaus

gases, unhindered entry of pollen (unpleasanfor allergy suf‐

ferers).

♦ A well regulated air conditioning system in conjunction with a

well thought-ouheating and ventilation system can create a

feeling of well-being and comforby regulating the interior

temperature, humidity and rate of air change, regardless of the

external conditions. This musbe available whether the vehi‐

cle is moving or not.

Other importanadvantages of air conditioning are:

♦ Drying of the air in the passenger compartmen(humidity in

the air condenses on the cold evaporator and is drained away

as condensate, the air is heated up again on the heaex‐

changer for heater to a presetemperature, which reduces the

water contenin the air and the absolute and relative humidity

is reduced).

♦ Additional cleansing of the air directed into the passenger

compartmen(dusand pollen thahave made their way

passed the dusand pollen filter, for example, are washed ou

by the moisfins of the evaporator and carried off with the

condensation water.)

♦ Temperatures in a mid-range car (for example, after a shor

period of driving, ambientemperature 30°C in the shade and

the vehicle in direcsunlight).

With air conditioning Withouair condi‐

tioning

Head heigh

Ches

Footwell

23 °C

24 °C

30 °C

42 °C

40 °C

35 °C

6.4.3

Environmental aspects

♦ Until abou1992, air conditioning systems were equipped with

refrigeranR12. Due to its chlorine atoms, this CFC had a high

potential for destroying ozone and, in addition, a very high po‐

tential for increasing the greenhouse effect.

♦ From 1992, the air conditioning systems of newly manufac‐

tured cars have been successively changed from R12 refrig‐

eranto R134a refrigerant. This refrigerancontains no

chlorine and therefore does no damage to the ozone layer.

Due to the high global warming potential of approx. 1400

(GWP), imay no longer be used in vehicles thaare newly

type approved from 2011. The cut-off date for bringing vehi‐

6. Basic technical and physical properties

27

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cles thawere type approved before 2011 into operation for

the firstime with R134a refrigeranis 31.12.2016 (this applies

to countries within the EU, differenregulations may apply in

countries outside the EU).

♦ After 01.01.2011, vehicles will only be given a new type ap‐

proval if the refrigeranused in the refrigerancircuiof their

air conditioning system has a GWP of less than 150. R1234yf

refrigeranhas a GWP of approx. 4 and is therefore markedly

below the prescribed level.

♦ From 2011, the air conditioning systems of newly manufac‐

tured cars have been successively changed from R134a re‐

frigeranto R1234yf refrigerant. This refrigeranhas a global

warming potential of approx. 4. The GWP of carbon dioxide =

lk

1 (global warming potential) and has much less of an impac

on the earth’s atmosphere than R134a refrigerant.

♦ Conversion programmes have been developed for old sys‐

tems filled with the ozone-depleting substance R12 ⇒ Work‐

shop manual for air conditioners with R12 refrigeran(this

workshop manual is available in paper form only).

♦ According to currenlegislation, R134a refrigeranmay still be

charged in vehicles thawere type approved for use with

R134a refrigeran(or in vehicles converted from R12 refriger‐

anto R134a refrigerant) until these vehicles are decommis‐

sioned. No provision has currently been made, therefore, to

converair conditioning systems from R134a refrigeranto

R1234yf refrigeran⇒ Air conditioning systems with R134a

refrigerant; Rep. gr. 87 ; Capacities for R134a refrigerant, re‐

frigeranoil and approved refrigeranoils .

♦ To protecthe environment, no refrigeranshould be released

into the atmosphere

⇒ “2 Legal texts and regulations”, page 5 .

♦ R1234yf refrigeranis chemically stable in an enclosed sys‐

tem. In the earth’s atmosphere, however, idecomposes with‐

in a shorspace of time (within approx. 14 days) by the

influence of UV lighinto compounds thado noharm the

earth’s atmosphere (hence the GWP of 4).

6.5

Other reference material

♦ Workshop manual for model-specific maintenance work ⇒

Heating, air conditioning system; Rep. gr. 87 ; Overview of

fitting locations - air conditioning system (vehicle-specific

workshop manual) and ⇒ Currenflow diagrams, Electrical

faulfinding and Fitting locations

♦ Technical Service Handbook with measures for rectifying lat‐

esmalfunctions

♦ Self-study Programmes, videos for workshop training and VW/

Audi TV episodes on the air conditioning system.

♦ The specific risks of refrigerant, material data etc. can be

gleaned from the safety data sheets. Safety data sheets abou

refrigerant, refrigeranoil etc. ⇒ VW / Audi ServiceNe.

♦ List of relevanspecial tools and workshop equipmenfor re‐

pairs to air conditioning systems ⇒ Electronic parts catalogue

(Tools; Workshop equipment/tools; Heating, air conditioning

system).

♦ Information abouthe disposal of refrigeranoil and contami‐

nated refrigerancan be found on ⇒ VW / Audi ServiceNe.

♦ For vehicles whose refrigerancircuiis charged with R134a

refrigeran(vehicles thawere type approved before

31.12.2010 and have been or are to be commissioned for the

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firstime by 31.12.2016

⇒ “2 Legal texts and regulations”, page 5 .

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6. Basic technical and physical properties

29

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Technical data Basic technical and physical properties for Your Volkswagen Sharan VAN Second Generation (2010-2023)

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