A/C System, Electrical Testing

A/C system, electrical testing


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

Test equipment required







- VAG1598 test box with adapter cables VAG1598/11, VAG1598/12 and VAG1594 adapter set
- Fluke 83 multimeter (US 1119) or equivalent
- US 1115 LED tester
- Thermometer

Requirements
- Battery Positive Voltage (B+) OK
- Ground (GND) connections on engine and transmission OK
- Fuse No. 42 (S42), 51 (S51), 225 (S225) and 15 (S15) OK


CAUTION!
Switch multimeter to the appropriate measuring range before connecting the test leads to avoid damaging electronic components.


VAG1598 test box, connecting
- Switch off ignition.
- Remove A/C control head -E87- and disconnect all connectors, -A-, -B-, -C- and -D-.







- Connect VAG1598/11 and 12 adapter cables to corresponding connectors of the vehicle wiring harness (to -E87-).
- Connect VAG1598 test box to the respective adapter cable for performing measurements.


NOTE:
- Do not connect -E87-.
- When using VAG1598/12 adapter cable, the terminal assignment of the sockets is identical with the terminal assignment of - E87-.
- When using VAG1598/11 adapter cable, the terminal assignment of the sockets is not identical to the terminal assignment of -E87-.


Connector terminal assignment of VAG1598 test box with VAG1598/11 adapter cable


NOTE:
- The terminal assignment of VAG1598/11 adapter cable connectors A and B is not identical to the terminal assignment of sockets on the VAG1598 test box.
- The terminal assignment of VAG1598/11 adapter cable terminal C is identical to the terminal assignment of sockets on the VAG1598 test box.
- The terminal assignment of VAG1598/12 adapter cable terminal D is identical to the terminal assignment of sockets on the VAG1598 test box
- As a result of splitting the connectors to A/C control head -E87- using two adapter cables (VAG1598/11 and 12), no ground connection exists for the test when VAG1598/11 adapter cable is connected. When performing various electrical tests, it is therefore necessary to use an external Ground source (vehicle body etc.) or a second VAG1598 test box (when adapter cable VAG1598/12 is connected, Ground exists at sockets 14 and 15).







Electrical testing


NOTE:
- VAG1598 test box must not be connected to A/C control head -E87- when performing On Board Diagnostic with VAG1551 Scan Tool (ST)
- Further notes, test requirements, connecting adapter cables and test equipment.
- From m.y. 1997, do not connect VAG1598 test box to -E87- for test steps 1.1 through 5.7. (Test box only to be connected for test steps 5.8, 5.9 and 5.10).

Test Number 1 - 6:

Test No. 1 (A/C control head -E87- voltage supply, ground connection)

Test Step 1.1 - 1.8:

Test Step 1.9 - 1.10:

Test No. 2 (Temperature Sensors -G17-, -G56-, -G89-, G191-, G192-.)

Test Step 2.1 - 2.5:

Temperature sensor resistances (based on ambient temperature, resistance in k ohm)







Test No. 3 (Fresh Air Blower -V2- and Control Module for Fresh Air Blower -J126-)

Test Step 3.1 - 3.4:

Test No. 4 (air/temperature distribution flap motors and related potentiometers)

Test Step 4.1 - 4.8:

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-)

Test Step 5.1 - 5.7:

Test Step 5.8 - 5.9:

Test Step 5.10:

Test Step 5.11:

Test No. 6 (A/C Clutch Relay -J44-, actuation of Coolant Fan -V7- stage 1)

Test Step 6.1 - 6.2:

NOTE:
The following test steps are only performed for A/C control heads -E87- with two displays:
- Test step 2.2 (the instrument panel interior temperature sensor -G56- is installed in A/C control heads -E87- with one display)
- Test step 5.7 (the interior temperature sensor fan -V42- is installed in A/C control heads -E87- with one display)

Test Step 1.15 - 1.16:

Test Step 1.17:

Test Step 5.9:

List of changes to electrical tests, 1998

Test Step 1.9 - 1.10:

Test Step 1.11 - 1.12:

Test Step 1.13 - 1.14: