Where is the blower resistor located in an Audi A4?
3 Answers
The blower resistor is located inside the blower assembly in the cabin and serves as a switch to regulate the fan speed. Function of the vehicle blower: When the blower is turned on, if the temperature is set to the lowest setting, the external circulation mode will draw in natural air from outside the vehicle, though slightly warmer. The air intake for the external circulation is typically located between the windshield lower edge and the engine compartment, which introduces some heat from the engine bay. In internal circulation mode, the air blown out will be at the temperature of the cabin. Components of the vehicle blower: The blower mainly consists of the following six parts: motor, air filter, blower body, air chamber, base (also serving as the oil tank), and oil drip nozzle.
The blower resistor of the Audi A4 is usually hidden behind the glove compartment on the passenger side. You'll need to remove the glove box to see it mounted on the blower fan assembly. I remember that for previous generations like the B7 or B8 A4, the location is roughly the same, but you'd better check the repair manual for specific year differences to be sure. The resistor mainly controls the fan speed. If it fails, the AC might only blow at high speed or stop working altogether, and it can easily blow a fuse causing hot air to blow uncontrollably. When troubleshooting, first disconnect the power, then use a screwdriver to remove the glove box screws and gently pull it out. You'll see a small black square resistor attached to the side of the fan. Unplug the connector and test the resistance value - it should normally be a few ohms. If the reading is too high or shows an open circuit, it indicates a fault and needs replacement. Dust accumulation and vibration are the main causes of failure, so it's recommended to clean the AC filter annually as prevention. DIY replacement isn't too difficult, but wear gloves to protect against cuts. If unsure, it's better to visit a professional shop for peace of mind.
As a long-time A4 owner, I once encountered the issue of the fan speed stuck in first gear, and later discovered the blower resistor was hiding behind the glove box on the passenger side. Removing the box is quite simple: first empty the contents, unscrew the two screws in the corners, and slowly pull out the box—the resistor is fixed to the blower, about the size of a matchbox. This was the case for my 2015 A4, and it's said that older models have it in the same location, while the newer B9 might have slight adjustments. When faulty, the fan speed goes out of control or the AC crashes, affecting driving comfort and draining power. Use a multimeter to check the resistor value; if it deviates from the standard, it needs replacement. Buying a part online for twenty bucks and replacing it in ten minutes can save hundreds in repair costs. For daily maintenance, the key is to prevent moisture from corroding the connectors, especially on rainy days.
