radiator AUDI A4 1998 B5 / 1.G AC System On Board Diagnostic Workshop Manual

temperature sensor are used as instantaneous
outside and engine temperature inputs for A/C
system control. If "standing time" is shorter than
4 hours, the actual measured values of the
outside temperature sensor are suppressed
and system output temperature control is
calculated by the A/C control head. The
"standing time" period is monitored and used
for this calculation. (Heat radiating from the
engine and radiator leads affects the measured
value of the temperature sensor).
Pa
ge 7 of 91 A/C s
ystem, On Board Dia
gnostic
(OBD
)
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.HA01.01.1

01-31

VAG1551 scan tool
display Possible cause
Corrective action
00801 3311
A/C Refrigerant High
Pressure Switch F118

Open circuit/short circuit to
positive /SP - Open circuit in wiring/connections between -F118-
and -E87-
- Malfunction in operation of coolant fan V7 (stage 1)


- Condenser or radiator dirty
- Malfunction of Coolant Fan V7 (stage 2) by A/C
Refrigerant High Pressure Switch F23
- -F23-/-F118-1) malfunction

- Refrigerant circuit malfunction- Diagnose and repair open circuit in
wiring using wiring diagram
- Test fan operation V7 (stage 1)
using
function 03 (Output DTM) page
01
-42

- -V7- electrical test page 01
-115
- Clean condenser and radiator
- Test V7 (stage 2) from -F23-
page 87
-64


- Test F23/F118 page 87
-64

(switching pressures)
- Check refrigerant system pressures
page 87
-192
.
1)F118 and F23 are integrated into the same housing.
Note:
If an open A/C Refrigerant High Pressure Switch -F118- was recognized 30 times during a driving period (e.g. because of a
loose contact), the compressor is switched off. Compressor can be switched on again by pressing "compressor on" button or
by switching ignition off and on. If this fault occurs over several driving periods, compressor cannot be switched on again until
DTC memory is erased.
Pa
ge 41 of 91 A/C s
ystem, On Board Dia
gnostic
(OBD
)
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.HA01.01.1

01-39

VAG1551 scan tool
display Possible cause
Corrective action
00792 3224
A/C Pressure Switch
-F129-

Short circuit to
ground /SP - Open circuit in wiring/connections between -F129-
and -E87-
- Malfunction in operation of coolant fan -V7- (stage 1)


- Condenser or radiator dirty.
- Malfunction in operation of coolant fan -V7- (stage 2)
by A/C pressure switch -F129-
- -F129- malfunction
- Excess or low refrigerant system pressure- Diagnose and repair short or open circuit
in wiring using wiring diagram.
- Test fan operation -V7- (stage 1) using
function 03 (Output DTM)
page 01
-42

- -V7- electrical test
page 01
-115
.
- Clean condenser and radiator.
- Test -V7- (stage 2) via A/C pressure
switch -F129- page 87
-67
).
- Test -F129- page 87
-67
.
- Check refrigerant system pressures
page 87
-192
.
Notes:

A/C pressure switch -F129- contains 2 switching elements. Via terminals 1 & 2, the compressor is shut off due to low or
excess refrigerant system pressure (switch open). Via terminals 3 & 4, the second speed coolant fan is switched on
(switch closed).
When -F129- terminals 1 & 2 open, excess refrigerant pressure is initially recognized by A/C control head -E87- and a
DTC is stored. If the measured outside temperature is between 0 C & 50 C (32 F & 122 F) and -F129- terminals 1 &
2 remain open for longer than 30 seconds, -E87- switches over from excess pressure to low pressure (Low pressure
switch function) page 01
-86
, Read measuring value block (Display group 01 compressor shut-off conditions).
Pa
ge 53 of 91 A/C s
ystem, On Board Dia
gnostic
(OBD
)
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.HA01.01.1