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1.8 Comfort
A basic requirement for concentrated and safe driving is the feel‐
ing of comfort in the passenger compartment. Especially when it
is hot and humid, comfort can be attained only through the use of
air conditioning. Of course, open windows, an open sunroof or
increased air ventilation can contribute to comfort, but they all
have certain disadvantages within the vehicle interior, such as
additional noise, draughts, exhaust gases, unfiltered entry of pol‐
len (unpleasant for allergy sufferers).
A well regulated air conditioning system in conjunction with a well
thought-out heating and ventilation system can create a feeling
of well-being and comfort by regulating the interior temperature,
humidity and rate of air change, regardless of the external con‐
ditions. This must be available whether the vehicle is moving or
not.
Other important advantages of air conditioning are
♦ The cleansing of the air directed into the passenger compart‐
ment. (Dust and pollen, for example, are washed out by the
moist fins of the evaporator and carried off with the conden‐
sation water.)
♦ Temperatures in a mid-range car (for example, after a short
period of driving, ambient temperature 30°C in the shade and
the vehicle in direct sunlight).
With air conditioning
system
Without air condi‐
tioning system
Head region 23℃ 42℃
Chest region 24℃ 40℃
Footwell 30℃ 35℃
1.8.1 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 thus does not
damage the ozone layer.
Up until about 1992, air conditioning systems were charged with
refrigerant R12. Due to its chlorine atoms, this CFC has a high
potential for destroying ozone and, in addition, a potential for in‐
creasing the greenhouse effect.
There are programs for exchanging old air conditioning systems
containing the ozone-damaging refrigerant R12.
⇒ Repair manual for air conditioning systems with refrigerant
R12 . This workshop manual is only available as a hard copy.
To protect the environment, no refrigerant should be released into
the atmosphere ⇒ page 39 (statutory texts and instructions).
1.9 How air conditioning works
The temperature in the passenger compartment depends on the
amount of heat radiated through the windows and conducted by
the metal parts of the body. In order to maintain comfortable tem‐
peratures for the occupants on very warm days, part of the
available heat must be pumped away.
Since heat spreads towards cooler bodies, a unit that can create
low temperatures is fitted in the vehicle interior. Refrigerant is
constantly being evaporated in it. The latent heat of evaporation
is taken from the air passing through the evaporator.
The refrigerant carries the heat with it as it is pumped away by the
air conditioner compressor. The work performed by the air con‐
Amarok 2011 ➤ , Beetle 2012 ➤ , Bora 1999 ➤ , CC 2010 ➤ , CC 2012 ➤ , ...
Air conditioning system with refrigerant R134a - Edition 10.2014
1. General notes on air conditioning systems 9
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