What is the definition of the four wires in the Audi A4 fan controller?
3 Answers
Audi A4 fan controller four-wire definition is the grounding wire from the temperature control switch, permanent live wire, relay output wire, and ignition live wire. The following is a related introduction about the Audi A4: 1. Introduction to the Audi A4: The Audi A4 (Audi A4) is a B-class vehicle manufactured by FAW-Volkswagen and launched in April 2003. 2. The transmission system of the Audi A4: In terms of power transmission, the Audi A4 3.0 is equipped with Audi's patented quattro all-wheel-drive system as standard, providing the vehicle with double the traction. This system enables the vehicle to automatically, accurately, and timely distribute the ground force of each wheel when turning or braking on various complex road surfaces, thereby improving the directional stability and traction of the vehicle under complex driving conditions.
The four wires of the Audi A4 fan controller are generally allocated as follows: the red or thick wire is the positive power supply, connected directly to the battery; the black or brown wire is the ground, which can be attached to the car body; the remaining two wires are usually control signal wires, one for the low-speed setting and one for the high-speed setting, both coming from the computer module. I've repaired many older A4 models in the workshop and found that some models also come with a speed feedback wire that connects back to the car's computer. For self-inspection, first check if the power and ground wires are conducting, then turn on the air conditioning to see if the control wires have a 12-volt voltage. Without professional equipment, avoid disassembling it randomly, as reversing the polarity in such circuits can easily blow fuses or the controller.
These four wires actually have distinct functions: one power supply wire connects to the fuse box or battery positive terminal, one ground wire is fixed to the metal frame in the engine compartment, and the other two are both signal control wires. The low-speed trigger signal activates at around 92 degrees Celsius, while the high-speed mode only engages at 105 degrees or when the AC is turned on. I've tested on the circuit board – the voltage changes on the signal wires are particularly noticeable. However, wire colors may vary across different model years, so it's best to check the repair manual for confirmation or use a multimeter to test continuity. By the way, if the fan isn't spinning, check the relay first – often the issue isn't with the controller itself.
