engine AUDI A4 1996 B5 / 1.G AC System Electrical Testing Workshop Manual

01-115


A/C system, electrical testing

Notes:

Vehicles 1997 page 01
-135
.

VAG1598 test box must not be connected to -
E87- when performing On Board Diagnostic
with VAG1551 Scan Tool (ST)

Test equipment required

Requirements
CAUTION!
Switch multimeter to the appropriate measuring range before
VAG1598 test box with adapter cables VAG1598/11, VAG1598/12
and VAG1594 adapter set Fluke 83 multimeter (US 1119) or equivalentUS 1115 LED tester ThermometerBattery Positive Voltage (B+) OK Ground (GND) connections on engine and transmission OK Fuse No. 42 (S42), 51 (S51), 225 (S225) and 15 (S15) OK
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01-119
Electrical testing, 1996

Note:
Electrical testing, 1997 page 01
-135
.
Test
number Component(s) tested:
Page
1
- A/C control head -E87- voltage supply, ground connection and illumination. Page 01
-
120

2
- Temperature sensors G17, G56 and G89 Page 01
-
122

3
- Fresh Air Blower V2 and Control module for fresh air blower J126 Page 01
-
124

4
- Air/temperature distribution flap motors and related potentiometers V68/-G92-, -V70-/G112,
V71/G113 and V85/G114) Page 01
-
126

5
- A/C compressor speed sender G111
- Refrigerant pressure switches -F118- and -F73-
- Interior Temperature Sensor Fan V42
- "A/C compressor intervention" output
- "Excessive engine temperature" signal Page 01
-
128

6
- A/C Clutch Relay J44
- Actuation for coolant fan stage 1 Page 01
-
133

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01-129

VAG1598/11 adapter cable Measuring range: Voltage measurement (20 V)
Test
step VAG1598
socket Test of
Test conditions
- additional steps Specified
values Corrective action
5.3 5 and
ground A/C Compressor Speed
Sender -G111-
Engine running Compressor not
running - less than 1
V - Determine and rectify short
circuit using wiring diagram.
VAG1598/11 adapter cable Measuring range: Voltage measurement (2 V)
Note: additional test steps before proceeding with this test. Test
step VAG1598
socket Test of
Test conditions
- additional steps Specified values
Corrective
action
5.4 5 and
ground A/C Compressor
Speed Sender -
G111-
Engine running Compressor running
- Relay for A/C Clutch removed
- Bridge terminals 30 + 87 at relay
connector base (A/C Clutch
switched on) - greater than 0.05 V
(depends on engine
speed) - Replace -G111-
page 87
-63
.
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01-132

VAG1598/11 adapter cable
LED voltage tester US 1115
Test
step VAG1598
socket Test of
Test
conditions
- additional
steps Specified values
Corrective action
5.8 13 + 12 "AC compressor
intervention" output
Engine
running - LED in voltage
tester does not come
on - Determine and rectify short
circuit to ground using wiring
diagram.
- Rectify cut-off condition for A/C
compressor in ECM.
- Rectify cut-off condition for A/C
compressor in TCM -J217-.
5.9 13 + 51 "Engine temperature
too high" signal Engine
running - LED in voltage
tester does not come
on - Determine and rectify short
circuit to ground using wiring
diagram.
- Rectify cut-off condition for A/C
compressor in Instrument Cluster.
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01-133
Test No. 6 (A/C Clutch Relay J44, actuation of Coolant Fan V7 stage 1) VAG1598/12 adapter cable Measuring range: Amperage (20 amps (A))
Test
step VAG1598
socket Test of
Test
conditions
- additional
steps Specified values
Corrective action
6.1 8 + 14 A/C Clutch
Relay -
J44-
Engine
running - less than 1 A
- Compressor
engaged and
running. - Determine and rectify open circuit or short circuit to
positive in wiring/connections between A/C Clutch -
N25-, -J44- and -E87- using wiring diagram.
- A/C Refrigerant Low Pressure Switch -F73- open,
test page 01
-131

- Replace -J44-.
- Repair or replace A/C Clutch -N25- page 87
-85
.
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01-134

VAG1598/12 adapter cable Measuring range: Amperage (20 amps (A))
Test
step VAG1598
socket Test of
Test
conditions
- additional
steps Specified
values Corrective action
6.2 16 + 14 Control of Coolant Fan
control (FC) relay -J26- (for
stage 1 operation of
Coolant Fan -V7-)
Engine
running - less than
1 A
- Fan runs
in stage 1. - Determine and rectify open circuit or short
circuit to positive in wiring/connections
between -J26- and -E87- using wiring
diagram.
- Check -V7- Repair Group 19
Note:
Testing operation of coolant fan via refrigerant high pressure switch F23 page 87
-64
.
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5
- A/C pressure switch -F129-
- "A/C compressor intervention" output
- "Excessive engine temperature" signal
- Interior temperature sensor fan -V42- Page 01
-
142

6
- A/C clutch relay -J44-, A/C clutch -N25-, actuation
- Coolant fan -V7-, actuation Page 01
-
146

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01-137

Adapter cable VAG1598/11
LED Voltage tester VAG1527B
Test
Step VAG1598
socket Test of
Test
conditions
- additional
work Specified Value
Corrective action
1.9 term.15 1) +
33 Signal for time
span ignition
off
Ignition
on - LED lights up - Diagnose and repair short or open
circuit in wiring/connections using wiring
diagram.
1.10 term.15 1) +
33 Signal for time
span ignition
off Ignition
on



- Start
engine. - LED lights up



- LED flickers briefly
(time signal) and then
lights up again - Diagnose and repair short or open
circuit in wiring/connections using wiring
diagram.
- Check signal from instrument cluster.
1) Terminal 15 (ignition) is available at -E87- connector -D-, terminal -9-.
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01-142
Test No. 5 (A/C pressure switch -F129-, "A/C compressor intervention" signal, engine temperature signal from
instrument cluster and Interior Temperature Sensor Fan -V42-) Adapter cable VAG1598/11
Measuring range: Resistance measurement (200 )
Test
Step VAG1598 socket
Test of
Test conditions
- additional work Specified Value
Corrective action
5.1 to
5.6 Not for 1997. A/C compressor speed sender -G111-, A/C high pressure switch -F118- and Low pressure switch -
F73- are no longer installed
Adapter cable VAG1598/11
Measuring range: Current measurement (20 A)
Test Step
VAG1598 socket
Test of
Test conditions
- additional work Specified Value
Corrective action
5.7 page 01
-131

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01-143

A/C control head -E87- connected to test box with adapter cable VAG1598/11
LED Voltage tester VAG1527B
Test
Step VAG1598
socket Test of
Test conditions
- additional work Specified
Value Corrective action
5.8 14 + 12 "A/C compressor
intervention"
output.
Engine
running. A/C
compressor
off
- Switch on A/C
compressor - LED lights
up


- LED lights
up slightly
dimmer. - Diagnose and repair open or short circuit in
wiring/connections using wiring diagram.
- Diagnose and eliminate A/C compressor
cut-off condition(s) from Engine Control
Module (ECM) or Transmission Control
Module (TCM)
- Diagnose and repair short circuit to ground
in wiring/connections using wiring diagram.
5.9 Ground
and
51 "Engine
temperature too
high" signal. Engine
running. - LED lights
up. - Diagnose and repair short circuit to ground
in wiring/connections using wiring diagram.
- Diagnose and eliminate A/C compressor
cut-off condition from Instrument cluster
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