coolant AUDI A4 1997 B5 / 1.G AC System Electrical Testing Workshop Manual

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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01-130

VAG1598/11 adapter cable Measuring range: Resistance measurement (200 ohm)
Test
step VAG1598
socket Test of
Test
conditions
- additional
steps Specified
values Corrective action
5.5 2 + 49 A/C Refrigerant High
Pressure Switch -F118-
- less than
20 W - Determine and rectify open circuit in
wiring or contact resistance using wiring
diagram.1)
- Replace -F118- page 87
-25
.
1)If code 1 "high-pressure switch -F118 open" is displayed in measuring value block 1 as a compressor cut-off condition: -Test
connections to -F118- for loose terminal using wiring diagram. -Test actuation of Coolant Fan V7 stage 1 Output Diagnostic Test Mode, page 01
-42
. Test actuation of Coolant Fan V7 stage 2 page 01
-42
. If no fault can be determined, check for
refrigerant system malfunction, refrigerant system pressure test page 87
-190
.
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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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01-145

Adapter cable VAG1598/11 connected.
Measuring range: Resistance measurement (200 ) Test
Step VAG1598
socket Test of
Test
conditions
- additional
work Specified
Value Corrective action
5.11 2 + 42 A/C pressure switch -
F129- (between
terminals 1 and 2)
Ignition
off - Less than
20
- Diagnose and repair open circuit or contact
resistance in wiring/connections using wiring
diagram.1).
- Check A/C pressure switch -F129- page 87
-67
.
1) If compressor cut-off condition code 1, "A/C pressure switch -F129- open" etc. appears in read measuring value block,
display group 1, display field 1: - check for intermittent contact in wiring/connections to -F129- using wiring diagram - check
function of Coolant Fan -V7- stage 1 with Output DTM (function
03)
page 01
-42
- check A/C pressure switch -F129- function
(actuation of -V7- stage 2, terminals 3 and 4 page 87
-67
). If no fault is determined, check A/C refrigerant system pressures
page 87
-190
.
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01-146
Test No. 6 (A/C Clutch Relay -J44-, actuation of Coolant Fan -V7- stage 1) Adapter cable VAG1598/12 connected.
Measuring range: Amperage measurement (20 A)
Test Step
VAG1598 socket
Test of
Test conditions
- additional work Specified Value
Corrective action
6.1 + 6.2 page 01
-133

Note:
Actuation of -V7- stage 2 via A/C pressure switch -F129- page 87
-67
.
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01-149

VAG1527 B Voltage Tester

A/C control head -E87- connected at test box (VAG1598/11 and /12 adapter cables)
VAG1598/11 adapter cable connected
Test
step VAG1598A
socket Test of
Test
requirements
- additional
operations Specified value
Corrective action
5.9 5) Ground
+
51 "Engine temperature
too high" signal
Engine
running
LED on
voltage tester
lights - Locate short circuit to Ground
and repair according wiring
diagram
- Eliminate A/C compressor cut-
off conditions in instrument
cluster
5) Only perform this test step for vehicles of m.y. 1997 or later
Notes:
Ignition key coding is transmitted to the A/C control head -E87- from the instrument cluster along with the coolant
temperature and the signal "engine temperature too high" when ignition is switched on for vehicles as of m.y. 1999 (data
message). Key coding can only be processed by A/C control heads -E87- with part number 8D0 820 043 after index "M."
No information can be transmitted if the coolant temperature is too high.
When ignition is switched on, A/C control head -E87- begins with the setting that was valid when the ignition was last
switched off with this key (temperature, air distribution, fresh air blower RPM).
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