Cooling fan issue

New to this forum so forgive me if this question has been answered already ...... My mother has a 2004 C3 1.4 petrol ...... We are having problems with the radiator cooling fan coming on as soon as the engine starts and running on for 3 or 4 minutes as soon as the engine is switched off. This issue is causing the battery to run down and needs to be re-charged every 2 or so weeks. The local garage have conducted done tests and say they need to replace the cooling fan module ..... which is effectively replacing the whole fan unit. If this does not work then it's the ECU. Does this sound right ? I have ordered a replacement cooling fan resistor unit (3pin) but cannot for the life of me see where this unit sits ....... I have removed the complete fan assembly and it's definitely not on that.
Any ideas or recommendations would be greatly relieved !

Hi, the cooling fan is a common problem on someone the petrol models.

Your diagnostics (you paid for?) said to change the fan unit assembly. It's a fan and some control but it depends very much on the model.

You could change the fan unit assembly that was suggested by the diagnostics. If it turns out to be the engine ECU you may be better off trading it in.

You may be trying to change a part that the garage, after their tests, did not suggest to change?

Maybe you have the wrong part?

There are two fans on the C3, one cools the engine radiator and one blows air into the cabin from outside.

Pictures can help, this topic will show you how to attach a picture.

how-do-i-use-the-c3-forum-f36/

As Arfur Dent says, a picture is worth at least a hundred words, so can you post a picture of this 3-pin module so that the experts amongst us can identify it?

I have attached a photo of the cooling fan resistor part ...... I thought it would fit on the radiator cooling fan unit but cannot see where. Someone mentioned it might be accessed through the n/s headlamp opening ?

Has anyone had experience with fitting a simple switch in order to turn the cooling fan off when the engine stops to save it over-running ?

Any ideas on why the cooling fan starts working as soon as the engine is started irrespective of temperature and keeps running on for 3 or 4 minutes when the engine is turned off ...... Would be most welcome