Get Technical data Basic technical and physical properties -> 6.4 Function and role of air conditioning system Guide for Volkswagen Sharan VAN Second Generation (2010-2023)

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Air conditioning systems with refrigeranR1234yf - General information - Edition 07.2017

♦ 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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Air conditioning systems with refrigeranR1234yf - General information - Edition 07.2017

♦ 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

♦ 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

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Air conditioning systems with refrigeranR1234yf - General information - Edition 07.2017

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 =

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

Rep. gr.00 - Technical data

Technical data Basic technical and physical properties -> 6.4 Function and role of air conditioning system for Your Volkswagen Sharan VAN Second Generation (2010-2023)

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