oil AUDI A4 1998 B5 / 1.G Refrigerant System Components Workshop Manual

87-21


Refrigerant system (R-134a),
components

A/C compressor


The compressor is driven via a belt on the engine when the A/C clutch
engages (A/C ON).
Low pressure refrigerant gas from the evaporator is compressed by the
compressor. After compression, the refrigerant gas (now high pressure)
flows to the condenser.
The variable displacement A/C compressor varies piston stroke and
output depending on load requirements and suction pressure.
Notes:
Zexel A/C compressors were installed from start of production. During
m.y. 1996, Nippondenso (Denso) type compressors are installed as a
running change. These compressors are not equipped with A/C speed
sensor G111. The compressor contains PAG type refrigerant oil that is mixable
under all temperatures with refrigerant R-134a. A label on the compressor indicates that compressor is for R-134a
systems only.
Pa
ge 1 of 13 Refri
gerant s
ystem
(R-134a
), com
ponents
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.HA01.87.6

87-22

Valve connections for pressure
switches


A Schrader valve is installed under A/C system pressure switches to allow
replacement without discharging the refrigerant system.
Note:
A/C system switches are available in different versions. Always refer to
the latest parts information to ensure correct switch application. - A/C system low and high pressure switches use different size threads.
- Use only the correct switches and O-ring seals specified for use with R-
134a refrigerant and PAG oil.
A - Switch connection (soldered)
B - O-ring seal
C - Schrader valve insert
Pa
ge 2 of 13 Refri
gerant s
ystem
(R-134a
), com
ponents
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.HA01.87.6

87-23


A/C compressor speed sensor -G111-, (Zexel compressors
only)

Note: - Inductive sensor (4 pulses per compressor rotation)
- Determines A/C compressor speed; the A/C compressor clutch control
module (Manual A/C) or the A/C control head (Automatic climate
control) compares compressor speed to engine speed and calculates
belt slippage (as a percentage) and switches compressor OFF if
slippage is too large (for example, if belt is too loose.)
A/C compressor speed sensor -G111- is not installed on Nippondenso
compressors. A thermo-fuse is incorporated into the clutch coil of Nippondenso
compressors. Current to the clutch coil is interrupted in the event of
compressor overheating.
Pa
ge 3 of 13 Refri
gerant s
ystem
(R-134a
), com
ponents
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.HA01.87.6

87-31

Accumulator


The accumulator traps the mixture of refrigerant vapor and gas coming
from the evaporator. While in the accumulator, the refrigerant vapor turns
to gas and, along with the refrigerant oil, is then suctioned by the
compressor.
An oil extraction passage is incorporated into the accumulator to ensure
that refrigerant oil flowing with the refrigerant does not remain in the
accumulator.
Any moisture in the system is absorbed by the desiccant in the
accumulator.
Note:
Do not remove caps -A- and -B- until ready to install new accumulator. If
caps are removed too soon, the dessicant becomes saturated with
moisture after a very short time. If this occurs, the accumulator must be
replaced.
Pa
ge 11 of 13 Refri
gerant s
ystem
(R-134a
), com
ponents
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.HA01.87.6

87-32

O-rings


O-rings seal the connections between components of the A/C system.
Use only O-rings which are compatible with R-134a refrigerant and
refrigerant (PAG) oil. Refer to the most recent parts information when
obtaining new O-rings.
Notes:
Handle O-rings only in a clean working environment.Do not reuse O-rings, always replace.Always use correct size O-rings (dimensions -a- and -b-).Lubricate O-rings with refrigerant (PAG) oil before installing.Always ensure O-rings are properly installed on pipe/component
mounting flanges/grooves. O-ring and torque specifications also apply to threaded connections in
the A/C lines.
Pa
ge 12 of 13 Refri
gerant s
ystem
(R-134a
), com
ponents
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.HA01.87.6

87-33

Hoses and lines

The mixture of refrigerant oil (PAG oil) and
refrigerant R-134a attacks some metals and
alloys (for example, copper) and breaks down
certain hose material. Use only hoses and lines
which are identified with the lettering "R-134a."
Hoses and lines are secured with threaded
connections. Always properly torque hose and
line connections.
Pa
ge 13 of 13 Refri
gerant s
ystem
(R-134a
), com
ponents
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.HA01.87.6