Why doesn’t the cooling fan (fan) in my Citroën C4 (especially the Pallas or Hatch 2.0) turn on at the correct speeds, causing overheating? What should I check besides the fuse?

In Citroën C4s, the cooling system is precisely controlled by the ECU, which operates the fan at two or three speeds (slow, medium, and fast).

• Chronic Failure: The most common problem is not the fan motor itself, but rather the… Resistance Module (also called a “resistor box”) that controls the first gear (slow). This resistor is responsible for reducing the electrical current, allowing the fan to rotate more slowly to maintain a stable temperature in urban traffic. Over time and with heat, this resistor tends to burn out.
• Symptoms:
  1. The engine quickly reaches high temperatures in traffic (above 95º).
  2. The fan only turns on when maximum speed (fast), usually with a loud noise, and late in the day (often above 100º or when the air conditioning is turned on).
• Solution: If the fan doesn’t turn on at low speed, the most likely diagnosis is a burnt-out component. Electric Fan Resistance Module. This part needs to be replaced. It’s also important to check the fan power fuse, usually a Maxi-Fuse with high amperage (Ex: 40A to 70A) in the BSM (under the hood). If the fuse is good and the cooling fan doesn’t turn on at idle, the resistor is burned out.