Audi A4: Refrigerant R134a
Refrigerant R134a Physical Data
Vehicle air conditioning systems make use of the
vaporization and condensation process. In this case, one works
with a substance which boils easily, designated as refrigerant.
The refrigerant used is tetrafluoroethane R134a, which boils
at -26.5 ºC (-15.7 ºF) at a vapor pressure of "1 bar (14.5 psi)"
(absolute pressure corresponds slightly to the ambient
pressure).
Critical Point
The critical point (critical temperature and critical
pressure) is that above which there is no longer a boundary
between liquid and gas.
A substance above its critical point is always in the
gaseous state.
At temperatures below the critical point, all types of
refrigerant in pressure containers exhibit both a liquid and a
gas phase, for example there is a layer of gas above the liquid.
As long as both liquid and gas are present in the container,
the pressure is governed by ambient temperature. Refer to
→ Chapter "Refrigerant R134a Vapor Pressure Table"vapor
pressure table".
Note
Different types of refrigerant are never to be mixed. Only
the refrigerant designated for the corresponding A/C system may
be used.
Refrigerant R134a Environmental Information
- R134a is a fluorocarbon and contains no chlorine.
- R134a has a shorter atmospheric life span than refrigerant
R12.
- R134a does not damage the ozone layer. The ozone depletion
potential is zero.
- The greenhouse potential of R134a (Global Warming Potential
= GWP) is approximately 1430 (the GWP of carbon dioxide = 1). To
reduce the influence of the greenhouse effect of the refrigerant
R134a, the European commission has committed that a vehicle from
the 01/01/2017 with refrigerant in the vehicle A/C system with a
GWP greater than 150 can no longer be placed on the market. A/C
system in vehicles which were brought into the market through
12/31/2016 can until further notice be filled with refrigerant
R134a and driven.
- The global warming effect of R134a is "10" times less than
that of refrigerant R12.
READ NEXT:
Commercial Names and Designations
Refrigerant R134a is currently available under the following
trade names:
H-FKW 134a
SUVA 134a
KLEA 134a
Note
Different trade names may be used in oth
General Information
Caution
When handling refrigerant oil, pay attention to
local regulations.
Refrigerant oil mixes with the refrigerant (about 20-40%,
depending on compressor type and amo
General Information
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 hot weather it is possibl
SEE MORE:
Overview - Rear Window
Overview - Rear Window, Sedan
1 -
Rear Window
Removing and installing. Refer to
→ Chapter "Rear Window, Removing and Installing".
Distance to roof: dimension -a- = 2 mm
Distance to C-pillars: dimension -d- =
approximately 3 mm; center if necessary
2 
Front Passenger Occupant Detection Sensor -G128-, Removing and Installing
Note
The passenger occupant detection sensor is only installed in the
front passenger seat.
Removing
- Unscrew the front passenger seat and tip to the rear with the
wires attached. Refer to
→ Chapter "Fr