What is the reason for the Peugeot 408 fan not working?

[McHaven]

In such cases, it is mainly due to issues with the fan circuit or problems with the control system. It is recommended to check whether the fan rotates after turning on the air conditioning. If it does not rotate, then there is definitely a problem with the fan circuit. Below is the relevant introduction: 1. Peugeot 408: The Peugeot 408 is a compact car launched by Dongfeng Peugeot on January 25, 2010, equipped with the mainstream engines of the DPCA, with two displacement options: 2.0L and 1.6L. The launch of the Peugeot 408 greatly enriched Dongfeng Peugeot's product line in the 1.6L-2.0L golden displacement market. 2. Model introduction: The maximum power of this CVTS-Ⅱ engine is 108KW/6000rpm, and the maximum torque is 200N.m/4000rpm, which is basically the same as the current 307's 2.0L engine. Although there seem to be no major changes, incorporating more new technologies on the basis of mature power is Dongfeng Peugeot's approach to seeking stability.

[Correia]

My Peugeot 408 had the same issue last time where the cooling fan refused to work. There are several areas to check for this problem. The most common culprit is a failed fan motor itself - especially when the carbon brushes are worn out or the coil is short-circuited. You can test this by running the engine with AC on for ten minutes, then touching the fan blades; if they don't move at all, it's definitely a motor issue.

The relay and fuse should also be inspected - they're located in the fuse box under the steering wheel. Find the 30A fan fuse, pull it out and check; replace it if blown.

Another tricky offender is a faulty coolant temperature sensor. When it fails, the car thinks the engine is still cool and won't command the fan to operate, causing the temperature gauge to spike while the fan remains idle.

Loose wiring connections or rodent-chewed wires are also common - my friend's car had oxidized connectors causing poor contact.

Important: If you see the coolant temperature warning light, stop the vehicle immediately. Continuing to drive could cause cylinder scoring in minutes, and replacing an engine would be devastatingly expensive.

[LeGabriela]

Last time I helped my brother fix the 408's cooling fan, it took me a while to figure out the issue. First, you need to determine whether the electric fan isn't spinning at all or if it's just not spinning fast enough. After starting the engine, turn on the AC—normally the fan should immediately switch to high speed. If it doesn't spin at all, directly check the 40A large fuse in the fuse box and the black square relay. You can test the relay by swapping it with another identical one, like the horn relay. If the fan suddenly starts working after the swap, then the relay is the culprit. For motor issues, you'll need to remove the fan assembly and test it directly with a 12V battery—that's the most accurate method. Wiring faults are the most troublesome, especially in the high-temperature areas of the engine bay where wires can age and fray. Another hidden culprit is the engine control unit (ECU). If its control signal fails, the fan won't move either—this requires a diagnostic scan at a 4S shop to read the fault codes. If you're working on it yourself, remember to disconnect the negative terminal of the battery to prevent short circuits and fires.

[StRemington]

A non-working fan can range from minor to serious, depending on the symptoms. If the temperature gauge needle keeps climbing toward the red line while the fan remains completely still, there's a 90% chance it's an electrical issue. The first thing to check is the fuse—the main fan fuse for the 408 is located in the engine compartment fuse box, marked as FS28, a 40A blue fuse. If it's blown, replacing it costs just a few bucks. A faulty relay might produce a clicking sound without the fan moving; sometimes, tapping it a couple of times can temporarily fix the issue. If the fan hasn’t been working for a long time, be wary of a seized motor bearing—a squeaky sound when it tries to spin is a red flag. Corroded or water-damaged connectors can also be problematic; unplug them and check for greenish pins. Those who’ve modified audio wiring should be extra careful, as messy wiring can interfere with the fan control module. Once, I worked on a six-year-old 408 where the issue turned out to be clogged gaps between the radiator and condenser with poplar fluff—the excessive load burned out the motor, which had to be replaced after cleaning.

[McLincoln]

Fan failure is usually caused by one of these four issues: First, the motor is dead—if you remove it and the blades feel stuck when turned by hand, it's done for. Second, there's a break in the power supply line—use a test pen to check if there's 12V at the plug. Third, the control signal is lost—if the ECU doesn't receive a signal from the temperature sensor, the fan won't start, manifesting as the fan not working whether the engine is cold or hot. Fourth, there's a system conflict—if the compressor kicks in when the AC is turned on but the fan doesn't follow, it's likely a burnt relay or a faulty AC pressure sensor. I recommend getting a can of carburetor cleaner to spray on the fan motor shaft and plug contacts; this can fix rust or poor contact issues. If you still can't find the problem, check the relay base contacts—last time I saw one melted and fused together, and replacing the base only cost 80 bucks.

[LePeter]

When repairing Peugeot vehicles, I often encounter fan failures mostly caused by a faulty temperature switch. There's a sensor with a two-pin connector near the thermostat - when this component malfunctions, it sends erratic signals. During cold starts, pour hot water on it; normally you should hear the relay click and the fan immediately start spinning. Another hidden issue is a failed fan resistor, which causes the low-speed setting to stop working while high-speed still functions. The diagnostic method is to directly short-circuit the resistor connector - if the fan immediately runs at full speed, the resistor is dead. For wiring issues, focus on the wire harness near the engine firewall. The 408's harness position is too low and prone to water splash corrosion. For modified headlights, always check the electrical connections - I once found an owner who tapped power from the fan relay for auxiliary lights, overloading the current and burning through the control board. During maintenance, recommend having the technician check the fan duty cycle data stream via OBD - it's much more accurate than visual inspection.