Pacciollo
Download the factory wiring PDF for your specific engine code (look on the driver’s side strut tower). Avoid aftermarket "universal" diagrams – they will mislead you.
Key Insight: The diagram reveals that pin 3 of the bitron box controls the low-speed fan via R5. If your fan runs only with AC on, consult the wiring schematic to check the ground at pin 85 of R5. peugeot 306 wiring diagram