Amarok 2011 ➤ , Beetle 2012 ➤ , Bora 1999 ➤ , CC 2010 ➤ , CC 2012 ➤ , ...
Air conditioning system with refrigerant R134a - Edition 10.2014
Temperature in °C
Pressure in bar (positive pres‐
sure) R134a
5
2.49
3.13
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
3.90
4.70
5.63
6.70
7.83
9.10
10.54
12.11
13.83
15.72
17.79
20.05
22.52
25.21
28.14
31.34
lk
1.5
Refrigerant R134a
Air conditioners in vehicles use the evaporation and condensation
process. The system contains a liquid with a low boiling point,
called the refrigerant.
The refrigerant used is tetrafluoroethane R134a, which boils at
-26.5°C with vapour pressure of 1 bar.
1.5.1
Physical data of refrigerant R134a
Chemical formula
Chemical designation
Boiling point at 1 bar
Freezing point
CH2F–CF3 or CF3–CH2F
Tetrafluoroethane
-26.5℃
-101.6℃
Critical temperature
Critical pressure
100.6℃
40.56 bar (technical) pressure
equates to 39.5 bar (standard)
pressure
1.5.2
Critical point
Critical point (critical temperature and critical pressure) means the
point above which there is no longer a surface of separation be‐
tween liquid and gas.
Above its critical point, a substance is always gaseous.
At temperatures below the critical point, all types of refrigerant
contained within a pressure tank exhibit a liquid phase and a gas
phase, so that there is a gas cushion above the liquid.
As long as there is gas in the pressure vessel alongside the liquid,
the pressure depends directly on the ambient temperature
⇒ page 3 .
4
Rep. gr.00 - Technical data
English 
