Peugeot 406 GLX cooling fans

It is likely that the switch you are referring to is the ignition switch, which is responsible for turning the electrical system on and off when the key is inserted and turned. The ignition switch is an important component of the Peugeot 406's electrical system, as it allows the vehicle to start and provides power to the electrical components when the engine is running.
If the ignition switch is not functioning properly, it can cause a variety of issues with the vehicle's electrical system, including problems with starting the engine, powering the dashboard lights and other electrical components, and controlling the fuel pump. It is important to have a functioning ignition switch in order to operate the vehicle safely and reliably.
If you are experiencing issues with the ignition switch or other components of the electrical system in your Peugeot 406, it is recommended to have the vehicle inspected and diagnosed by a professional mechanic. They will be able to identify any problems and determine the necessary repairs.

you car is showing a code if so what one and with FAN not belt they usually stay one to cool vehicle for a few minutes as to noise if rattle can be bracket or fan failing if loud wind thats normal

They start when the engine temperature reaches about 220F

depending on the engine temperature the fan is supposed to remain on after you turn the engine off, until the engine reaches a preset cooler temperature. when it reaches cooler temperature usually within 5 minutes or so it should cut off... if you cut it off and it is running 30 minutes later.. then there is a problem with the fan relay or temperature sending unit.

I beleve all vehicles would have a blower motor resistor. Go to your parts place and ask them for a price on the blower motor resistor and ask for a print out location, they will give you one. Resistor is normally located around the motor.

if fan isnt working , water most proberly evaperating when getting hot , try wiring the fan so running constant

change the switch / balast resister

the problem may be with the 2 relays between the cooling fans the plug conectors corrode and damage the relays
recomend you replace connectors and relays

I have 1996 Peugeot 406 (1.8 16v) and it's ignition coil pack was broken and the starting was difficult when the car was warm.  

possible air mass or throttle position sensor