lock AUDI A4 1995 B5 / 1.G AC System On Board Diagnostic User Guide

01-36

VAG1551 scan tool
display Possible cause
Corrective action
01272 4123
Central Air Flap
Motor -V70-

Blocks or de-
energized /SP - Short circuit, open circuit in wiring or incorrect terminal
assignment (wires interchanged) of connectors between -
V70- and -E87-
- Central flap sticking
- -V70- malfunction- Diagnose and repair short circuit,
open
circuit or confirm terminal assignment
using wiring diagram
- Check for free operation of central
flap
- Test -V70- using function 03 (Output
DTM)
page 01
-42

01273 4124
Fresh air blower V2

Control
difference /SP - Short circuit or open circuit in wiring between V2, control
module for fresh air blower J126 and/or -E87-
- Open circuit in voltage supply or ground connection to -
J126-
- -J126- malfunction
- -V2- mechanical malfunction.- Diagnose and repair short circuit or
open circuit in wiring using wiring
diagram

- Diagnose and repair open circuit
using
wiring diagram
- -J126- electrical test page 01
-115
- Replace -V2-
01274 4131
Air flow flap motor
V71
- Short circuit, open circuit in wiring or incorrect terminal
assignment (wires interchanged) of connectors between
V71 and -E87-
- Air flow flap sticking- Diagnose and repair short circuit,
open
circuit or confirm terminal assignment
using wiring diagram
Pa
ge 48 of 91 A/C s
ystem, On Board Dia
gnostic
(OBD
)
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yp
e=re
pair&id=AUDI.B5.HA01.01.1

Blocks or de-
energized
/SP - -V71- malfunction. - Check for free operation of air flow
flap
- Test -V71- using function 03 (Output
DTM) page 01
-42

Pa
ge 49 of 91 A/C s
ystem, On Board Dia
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(OBD
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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
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ystem, On Board Dia
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01-40

VAG1551 scan tool
display Possible cause
Corrective action
01206
Signal for time span
ignition off1)

implausible
signal /SP - Short or open circuit in wiring/connections
between instrument cluster and -E87-
- Instrument cluster malfunctioning.- Diagnose and repair short or open circuit in
wiring using wiring diagram.
- Check signal from instrument cluster using
function 08, Read measuring value block
page 01
-86
.
01274 4131
Air Flow Flap Motor -
V71- 2)

blocked or no
current /SP - Short or open circuit in wiring/connections
between -V71- and -E87-.
- Air flap or fresh/recirculated air flap
binding/sticking
- -V71- malfunctioning.- Diagnose and repair short or open circuit in
wiring using wiring diagram.
- Check air flap or fresh/recirculated air flap for
ease of movement.
- Check -V71- using function 03, Output
Diagnostic Test Mode (DTM) page 01
-42
.
1) If A/C control head -E87- is unable to determine the duration of time when ignition is off ("standing time"), DTC 01206
"signal for time span ignition off" is loaded into memory. The A/C control head will then default to a standing time greater than
4 hours. The actual measured values of the outside temperature sensor are then used as instantaneous outside and engine
temperature inputs for A/C system control. When the "heating" mode is selected under these conditions, the fresh air blower -
V2- has a delayed start (even when the actual standing time is less than 4 hours and the engine is warm) page 01
-86
,
Read measuring value block. The outside air temperature display -G106- may also indicate incorrect outside temperature
values.
2) -V71- operates the air flow flap as well as the fresh/recirculated air flap.
Pa
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ystem, On Board Dia
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If the readout "function unknown or cannot be
carried out at the moment" appears in the
display page 01
-63
, Read measuring value
block (display group 1).
Function is unknown or cannot be carried out at the moment!

Indicated on display
- If this readout appears in the display, output Diagnostic Test Mode
(DTM) is ended.
- VAG1551 Scan Tool (ST) can be returned to the function mode by
pressing the button.
Pa
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ystem, On Board Dia
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01-46
Output Diagnostic Test Mode (DTM) table

VAG1551 scan tool display
Specified function
Corrective action
A/C Clutch N25








Notes: - N25 clicks every 2-seconds
- Output of A/C control head -E87- is switched from 0 V to
12 V every 2-seconds2) - Test voltage supply for -
N25- (via A/C Clutch
Relay J44) using wiring
diagram
- Repair or replace -N25-
page 87
-90

- Test circuit and
connectors between A/C
control head -E87-, J44
and -N25- using wiring
diagram
- Replace -E87-

"A/C compressor on" output to
Engine Control Module (ECM)
and -E87- terminal -C12- is
also actuated at the same
time1)
Output of -E87- switched from 0 V to 12 V every 2
seconds can be confirmed by switching compressor on
and off using the "ECON" button while reading the
measured value block of engine control module
Repair Manual, Fuel Injection and Ignition System,
Repair Group 01)

1)Test this "A/C compressor on" signal only if complaints exist. ECM uses signal to compensate for engine load when
compressor engages Repair Manual, "Fuel Injection & Ignition," Repair Group 24 . ECM is capable of switching off the A/C compressor from this signal. Confirm via function 08, Read measuring value block,
page Page 01
-63
, display group 01 and Fuel Injection and Ignition System Repair Manual, Repair group 01: Read
measured value block of ECM with engine running and at same time switch compressor on and off.
Pa
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2)A/C Clutch -N25- cannot be actuated during Output DTM when certain compressor cut-off conditions exist, page 01
-63
,
Read measuring value block.
Pa
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01-63

Read Measuring Value Block (function
08)


Notes:
10 measuring value blocks each containing 4
measured values are available.
When performing read measuring value block,
function 08:
Control of A/C system is possible (compressor
runs, air distribution control is possible etc.)

Pa
ge 91 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