My extractor fan is leaking a lot of water, it is nothing to do with the weather as it happens when it is not raining. The extractor fan was working but now has stopped

is the water leak allowing the water to wick up into the headliner or is the headliner getting wet without water coming past the weather stripping around the door?

If it is wicking then fix the weather stripping.
If the water is getting headliner wet with out passing the weather stripping then you have a leaking sun roof.

You can the door seal by sitting in the car while you have some spray water (garden hose) gentle at the frontal and upper door seal.
If not leak there inspect seal of sun roof and real seal with correct type of sealant.

sometimes even when seals look ok,they are not.

These water leaks can be really tough to find. In some cases the windshield seal can be leaking and the water runs down the firewall into the interior.
I have a similar issue on my Aurora from time to time. I believe the issue is the weather strip around the door seals. It looks to me like the water follows the weather seal and then is wicked into the car where the carpeting contacts the weather seal. I have thought about putting small holes in the weather seal on the bottom edge (facing the exterior of the vehicle) so that the water has a path to follow out of the car. Not sure if this will work.

needs new heater core

Have you been adding any coolant? You could have a leaking heater core, which will usually leak to the inside, wetting the carpets in the well. Most American cars locate the heater core on the passenger side of the firewall, so a leak will typically show up on only the passenger side floor. I once had an Audi that had the heater core mounted just about dead center on the firewall. When it started leaking, both sides of the well(s) got wet.

most likely cause is water intrusion through the cabin filter

pull the filter
if wet then you need to find something that diverts water away
many OEM's have had this problem but nothing on file for this vehicle

Check the door weather stripping for rips. If it only leaks when driving, check the floorpan for rust holes.

Seal the cowl cover on the passenger side of car.There is a technical service bulletin from Ford about your problem.

pop the hood and take out the plastic shroud on the passenger side at the firewall. there is a rubber weather stripping that will direct the rain water off the wind shield other wise the rain will fall directly onto the top of the fan motor then run down onto the carpet. i noticed mine when the fan motor iced up and was about an inch thick of ice. all i did was RTV on the weather stripping to redirect the water good luck.

Hi
We have sealed leaking extractor fans with clear sealant,advised after calling the manufactures (it was out of guarrante)