Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSAUDI199590 QUATTRO SPORT V6-2.8L (AAH)REPAIR AND DIAGNOSISHEATING AND AIR CONDITIONINGTESTING AND INSPECTIONCOMPONENT TESTS AND GENERAL DIAGNOSTICSELECTRICAL TESTINGAUTOMATIC CLIMATE CONTROL
1995 Audi 90 Quattro Sport V6-2.8L (AAH)
Automatic Climate Control
1995 Audi 90 Quattro Sport V6-2.8L (AAH)SECTION Automatic Climate Control
CAUTION:
- Do not connect VAG1598/11 or VAG1598/12 adapters to the A/C control head itself for electrical tests or damage to the control head will result.
- With the VAG1598/11 adapter, test box socket numbers do not match the terminal numbers on the A/C control head connectors; terminal identification.
- To avoid damaging electronic components, switch the measuring range on multimeter Fluke 83 (or equivalent) be fore making connections to test sockets.
Tools Required:
- Multimeter Fluke 83 (or equivalent)
- VAG1598 test box with VAG1598/11 and 1598/12 adapter cables
- VW1594 connector test kit
- VAG1527B voltage tester
- 91120 dial thermometer (or equivalent)
Electrical Testing:
- Check all fuses are OK per Wiring Diagram.
- Switch ignition off.
- Remove A/C control head -E87-. Control Assembly
- Connect VAG1598/11 and VAG1598/12 adapter cables to A/C control head harness connectors -A-, -B-, -C- and -D-
- Leave A/C control head disconnected.
NOTE: The VAG1598/11 and VAG1598/12 adapters cannot be simultaneously connected to the VAG1598 test box. VAG 1598 Test Box, Connecting
Electrical Test Tables:
Requirements:
- Set multimeter Fluke 83 (or equivalent) to the 20 K ohm resistance measuring range
- Connect VAG1598 test box with VAG 1598/11 adapter
- Connect multimeter to VAG1598 socket numbers indicated
Requirements:
- Set multimeter Fluke 83 (or equivalent) to the 200 K ohm resistance measuring range
- Connect VAG1598 test box with VAG1598/12 adapter
- Connect multimeter to VAG1598 socket numbers indicated
Requirements:
- Set multimeter Fluke 83 (or equivalent) to 20 volt DC voltage measuring range
- Connect VAG1598 test box with VAG1598/11 adapter cable.
- Connect multimeter to VAG1598 socket numbers indicated
Requirements:
- Use VAG1527B voltage tester
- Connect VAG1598 test box with VAG1598/11 adapter
- Connect LED tester to VAG1598 socket numbers indicated
- Do not connect VAG1598/11 or VAG1598/12 adapters to the A/C control head itself for electrical tests or damage to the control head will result.
- With the VAG1598/11 adapter, test box socket numbers do not match the terminal numbers on the A/C control head connectors; terminal identification.
- To avoid damaging electronic components, switch the measuring range on multimeter Fluke 83 (or equivalent) be fore making connections to test sockets.
Tools Required:
- Multimeter Fluke 83 (or equivalent)
- VAG1598 test box with VAG1598/11 and 1598/12 adapter cables
- VW1594 connector test kit
- VAG1527B voltage tester
- 91120 dial thermometer (or equivalent)
Electrical Testing:
Harness Connectors:
- Check all fuses are OK per Wiring Diagram.
- Switch ignition off.
- Remove A/C control head -E87-. Control Assembly
- Connect VAG1598/11 and VAG1598/12 adapter cables to A/C control head harness connectors -A-, -B-, -C- and -D-
- Leave A/C control head disconnected.
NOTE: The VAG1598/11 and VAG1598/12 adapters cannot be simultaneously connected to the VAG1598 test box. VAG 1598 Test Box, Connecting
Electrical Test Tables:
Resistance Values of Temperature Sensors:
Test Step 1 thru 6:
Requirements:
- Set multimeter Fluke 83 (or equivalent) to the 20 K ohm resistance measuring range
- Connect VAG1598 test box with VAG 1598/11 adapter
- Connect multimeter to VAG1598 socket numbers indicated
Test Step 7 thru 10:
Requirements:
- Set multimeter Fluke 83 (or equivalent) to the 200 K ohm resistance measuring range
- Connect VAG1598 test box with VAG1598/12 adapter
- Connect multimeter to VAG1598 socket numbers indicated
Test Step 11 thru 13:
Requirements:
- Set multimeter Fluke 83 (or equivalent) to 20 volt DC voltage measuring range
- Connect VAG1598 test box with VAG1598/11 adapter cable.
- Connect multimeter to VAG1598 socket numbers indicated
Test Step 14:
Requirements:
- Use VAG1527B voltage tester
- Connect VAG1598 test box with VAG1598/11 adapter
- Connect LED tester to VAG1598 socket numbers indicated
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.