406 thermo switch - where is it?

[Eastern Counties]

I've recently bought a 1996 1.9 diesel Peugeot 406. I discovered at the weekend that the radiator fans aren't coming on. I've been looking for the thermo-switch in the side of the radiator so that I can bypass it to check that the fan motors are OK. Apparently for my model it has a blue 3-pin connector with a red ring around it, but I can't find it.

So.... where exactly is the switch???
Any guidance/ drawing /photo would a great help.

[DocBrown]

The switch may be located on the thermostat housing. Not too familiar with 406 TD but the comparable Xantia with same engine has cooling fan sensor on thermostat housing. If your car has aircon then there might be two sensors - one being the Bitron sensor.

With ignition off and engine cold, check to see if the cooling fans spin freely without roughness or noise as seized or worn motor bearings will lock up the fans causing overheating. Important to make sure engine is cold as some cooling fans can start up after a run even if ignition is off. (prevents heat soak after a long run/adverse temperatures)

If you are certain the radiator lacks any sensors or switches, you will probably find the thermoswitch on the thermostat housing/cylinder head area where coolant exits the head via the top hose.

Doc

[Eastern Counties]

Thanks for your reply, Doc. I've had a look and yes, there are 2  sensors on the thermostat housing, one brown and one blue. My 406 doesn't have aircon.

With the weather being so hot, I got the 406 up to temperature idling in the sun and discovered that both fans do come on after all (very quietly), at a pretty fast speed, but only when the temperature gauge is nearly at 100. The fans go off when the ignition is turned off, whereas I am sure that on our Xantia they used to run independently of the ignition circuit. 100 degrees seems a bit late to cut in. I've found 3 relays in a triangular black box in between the fans. Perhaps one has packed up and that's why the fans don't run on their own. But why 3? Are the fans supposed to run at 2 speeds?

The old BXs were much easier - just a thermoswitch in the radiator that you could easily by-pass and have a cabin switch in an emergency.

Anyway, thanks again

John

Ps What is a Bitron? Sounds a bit like Citroen.