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 MANUALSAUDI1998A4 AVANT QUATTRO, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)EXTERNAL PAGESDIFFERENT CARSECTION 16 (AUTOMATIC A/C-HEATER SYSTEMS)SYSTEM TESTSFRESH AIR BLOWER & FRESH AIR BLOWER CONTROL MODULE
1998 Audi A4 Avant Quattro, Automatic
Fresh Air Blower & Fresh Air Blower Control Module
1998 Audi A4 Avant Quattro, AutomaticSECTION Fresh Air Blower & Fresh Air Blower Control Module
WARNING: This page is about a different car, the 2001 Audi S4, 2001 Audi A4, 2000 Audi S4, and 2000 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.
- Using Adapter Cable (VAG 1598/11) and DVOM in 20-volt range, check voltage between adapter cable terminal No. 16 and ground with ignition on. Voltage should be less than 5 volts and blower should not operate. If conditions are not as specified, check for short to battery voltage in Green/Black wire between fresh air blower control module and A/C-heater control panel. Check fresh air blower control module. Repair or replace as necessary.
- Check voltage between adapter cable terminal No. 14 and ground with ignition on. Battery voltage should exist. If battery voltage does not exist, check Black/White wire between A/C-heater control panel and fresh air blower. Repair as necessary.
- Check voltage between adapter cable terminal No. 11 and ground with ignition on. Battery voltage should exist. If battery voltage does not exist, check Brown/Green wire between fresh air blower control module and fresh air blower. Repair as necessary.
- Connect LED Voltage Tester (VAG 1527B) between Adapter Cable (VAG 1598/11) terminals No. 14 and 16. Turn ignition on. Ensure LED illuminates and fresh air blower operates. If conditions are not as specified, check for open circuit in wiring between fresh air blower control module and A/C-heater control panel. Ensure fresh air blower operates freely. Repair or replace as necessary.
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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.