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

01-2

Notes:

This Repair Manual describes On Board
Diagnostic (OBD) with VAG1551 Scan Tool
(ST). OBD procedures can also be performed
with VAG1552 Scan Tool (ST) (VAG1552 Scan
Tool is not equipped with a printer).
Scan Tool VAG1551 or 1552 must be used in in
operating mode -1- (Rapid data transfer).
Operating mode -2- (Flash code output) is not
provided for A/C and Heating OBD.
Always check DTC memory and perform
necessary repairs before erasing DTC memory.
DTC output is possible only if ignition is on or
engine is running and engine speed is less than
3000 rpm (if engine speed is higher, output is
possible only for a limited time or is terminated).
If a fault exists for a certain time it is stored as a
static fault.
If a static fault is no longer present after a
certain time, it is stored as a sporadic fault and
the reference "SP" appears on the upper right
of the VAG1551 display/print-out.
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01-3

Notes:

A/C system component locations: engine
compartment page 87
-96
.

A/C system component locations: passenger
compartment page 87
-106
.

If a the display of a newly installed A/C control
head -E87- flashes after switching the ignition
on (for approximately 2 minutes), code the
control head page 01
-57
and execute basic
setting page 01
-52
.

If a replacement control head is not coded after
installation or if an unrecognized code was
entered, code "00042" (4-cyl. gasoline engine
USA) is stored.
Control of A/C compressor, flap motors and fan
motors etc. is not possible when executing
Output Diagnostic Test Mode (DTM), function
03 and basic setting, function 04. A/C control is
possible in all other functions.
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01-4

Heating and A/C system changes, 1997


On Board Diagnostic changes

New A/C control head -E87- with specific
coding for m.y. 1997, 4-cyl. and 6-cyl. engines.

Notes:
Before performing On Board Diagnostic of A/C
system, ensure A/C control head -E87- is coded
correctly (according to engine application).
A/C control heads beginning with Part No. 8L0
820 043 should only be installed in m.y. 1997
vehicles.
A/C control heads beginning with Part No. 8D0
820 043 must only be installed in vehicles
through m.y. 1996.

CAUTION!
Part numbers are for reference only.
Always check with your Parts Dept. for the
latest information.
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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).
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01-7

A/C system changes

Revised heating/air conditioner assembly with
flap motors page 87
-174
.

The air flow flap motor now activates the fresh
air/recirculating air flap as well.
The two way valve for the circulating/fresh air
door, the vacuum unit and the vacuum reservoir
are deleted.

A/C refrigerant circuit changes
New service valve connection on low pressure
side.
Service valve connection for high pressure side
installed in high pressure line in plenum panel
(deleted at condenser).
A/C pressure switch -F129- replaces pressure
switches -F73- and -F118-.
New version "Zexel" compressor and high
pressure line (4-cyl. engines only).
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01-8

VAG1551 Scan Tool (ST), connecting;
A/C control head -E87-, checking
version


Battery Voltage OK
Fuse 22 (S22) OK
Ground (GND) connection on engine and
transmission OK

1996 vehicles

- Open rear passenger ashtray in center console and remove cover for
Data Link Connector (DLC).
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01-10

1997 vehicles

All vehicles - With ignition switched off, connect VAG1551 (VAG1552) scan tool to
16-pin Data Link Connector (DLC) under dash to left of steering
column, using adapter cable VAG1551/3.
V.A.G - ON BOARD DIAGNOSTIC HELP1 - Rapid data transfer2 - Blink code output

Indicated on display 1) 1) Operating modes 1 and 2 are displayed alternately
- Switch on printer with -PRINT- button (indicator lamp in switch will light
up).
- Switch on ignition or start engine.
- Switch A/C compressor on (press "AUTO" button).
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01-13

8D0820043D A4-Klimavollautomat DXX
Coding 00062 WSC ZZZZZ

Indicated on display after approx. 5 seconds
Readout example shows US/CDN version, Zexel A/C compressor, 6
cylinder gasoline engine
Coding -E87- and code tables page 01
-57
.
8D0 820 043 D: Part Number of A/C control head -E87-A4: A/C Heating Electronics component designationDXX: Software version of A/C control head -E87-Coding: 00062WSC 06812: Dealership code
8L0 820 043B A4-
A/C full
y automatic DXX
Codin
g XXXXX
WSC ZZZZZ

For m.y. 1997 vehicles install only A/C control head -E87- with Part No.
8L0 820 043 up to and including Part No. index letter "C."
8L0 820 043D A4-
A/C full
y automatic DXX
Coding XXXXX
WSC ZZZZZ

For vehicles beginning m.y. 1998 install only A/C control head -E87- with
Part No. 8L0 820 043 from Part No. index letter "D."
CAUTION!
Part numbers are listed here for reference only. Always check with
your Parts department for the latest information.
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01-14

Part
number Comments
8D0 820
043 D - G
Regulation is only switched off in
On Board Diagnostic (OBD)
during output diagnostic test
mode and basic setting.
For vehicles with 6 cylinder
engines, must only be combined
with Zexel compressor.
8D0 820
043 after
H For all vehicles up to m.y. 96.
8L0 820
043 A - C For all vehicles up to m.y. 97 (lighting
via terminal 58 and 58d)
8L0 820
043 after
D For all vehicles up to m.y. 98 without
radio navigation system up to VIN
199999 of m.y. 1999 (lighting
indirectly activated via terminal 58s).
8D0 820
043 K or L Version with only one display (for
vehicles with radio navigation system
up to VIN 199999 of m.y. 1999)
8D0 820
043 after
M Version with only one display (for
vehicles as of VIN 200000 of m.y.
1999)
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Parts catalog microfiche
Depending on VAG1551 Scan Tool (ST) program card version, 1st and 2nd digit may not
be displayed (readout: e.g. 040 instead of
00040).
Software version of control head is of no
significance for service department.
If a replacement control head is not coded after
installation or if an unrecognized code was
entered, code "00042" (4-cyl. gasoline engine
USA) is stored.
Pa
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play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.HA01.01.1