Fan wont go off

[A8 Owner]

In the centre of the scuttle under windscreen, theres a black box. Inside there a fan is on all the time. So flat battery all the time. Steve looked at fuses Block yellow fuse numbers 4,5,7,8,10 pulled each out to stop it. None of them did tho. Any ideas?
I have had the water problem in the pass side, in the sense it keeps getting blocked at the orange plug. At the moment the orange bit isnt connected up, as i have a hose pipe connected to the downpipe to catch any rubbish.in a bowl.
If i put finger over end of pipe i can feel the air blowing from the fan, if that helps work out what the problem is.
Now to top it of cant let battery run flat as it sets alarm off and wont turn off
So will havto leave this fan running over night while charger is plugged in, Only way to stop alarm going off.
NOT MY DAY