Volkswagen Golf Service & Repair Manual: Comfort
| A basic requirement for concentrated and safe driving is the
feeling 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 pollen (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 conditions. 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
compartment. (Dust and pollen, for example, are washed out by
the moist fins of the evaporator and carried off with the
condensation 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). |
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With
air conditioning system |
Without air
conditioning system |
| Head region |
23°C |
42°C |
| Chest region |
24°C |
40°C |
| Footwell |
30°C |
35°C |
Environmental aspects
| Since about 1992, the air conditioning systems of newly
manufactured 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 increasing 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
→ Chapter (statutory texts and instructions). |
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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
temperatures 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 conditioner compressor on the refrigerant increases its
heat content and its temperature. Its temperature is now
considerably higher than that of the ambient air. |
| The hot refrigerant flows with its heat content to the
condenser. There the refrigerant looses its heat through the
condenser to the surrounding air due to the temperature gradient
between the refrigerant and the surrounding air. |
| Thus, the refrigerant is a means of heat transport. Because
it will be needed again, it returns to the evaporator. |
| All air conditioning systems basically depend on the
circulation of refrigerant. However, there are differences in
the construction of the system. |
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Refrigerant machine oil is miscible (approx. 20%–40%
depending on the type of air conditioner compressor and the
quantity of refrigerant) in the refrigerant. I ...
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