Audi Q5 2008 - Page 23

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Water boils at a lower temperature the lower the pressure.
The vapor pressure curves for water and refrigerant R134a show
that, at constant pressure, reducing the temperature changes va‐
por to liquid (in the condenser) or that reducing the pressure
causes the refrigerant to change from liquid to vapor (inside the
evaporator).
Vapor Pressure Curve Of Water
A - Liquid
B - Gas
C - Vapor pressure curve of water
1 - Pressure acting on liquid in bar (absolute)
2 - Temperature in °C
Vapor Pressure Curve Of Refrigerant R134a
A - Liquid
B - Gas
D - Vapor pressure curve of refrigerant R134a
1 - Pressure acting on liquid in bar (absolute)
2 - Temperature in °C
1.3.3 Comfort
Being comfortable while driving leads to better concentration and
safe driving. Air conditioning makes drivers and passengers more
comfortable when temperatures or humidity are high. Comfort can
of course also be enhanced by opening windows/sun roof or in‐
creasing the air output, such a course of action is however asso‐
ciated with certain drawbacks for the occupants of the vehicle,
such as more noise, draughts, exhaust fumes and unfiltered pol‐
len (unpleasant for allergy sufferers).
Climate control together with a good heating and ventilation sys‐
tem concept can create a sense of well-being and comfort by
regulating temperature, humidity and air circulation in the pas‐
senger compartment to suit ambient conditions. This is done both
when the vehicle is moving and when it is stationary.
Air conditioning also offers these advantages:
♦ It cleans the air that enters the vehicle interior. The damp fins
on the evaporator collect dust and pollen, which is then re‐
moved by condensation.
♦ Temperatures in a mid-size vehicle (for example: after a short
drive, outside temperature 30° C in the shade and the vehicle
exposed to sunlight).
With A/C System Without A/C System
Head area 23° C 42° C
Upper body area 24° C 40° C
Foot area 30° C 35° C
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...
Refrigerant R134a Servicing - Edition 01.2011
1. General Information 19