Get General information on air conditioning systems -> How air conditioning works 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

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.

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

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

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