The climate control has a big pipe on the back sucking quite hard ,there is meant to be a piece of sponge in the climate control unit it is not a filter it is a noise damper but as usual ford used crap sponge that has perished over time like the stuff on the roof lining ,get a piece of sponge place it on the outside of the slit and see if this stops the noise if yes you fit it on the inside but you will need to glue it or it will get sucked down the pipe ,mine still has the original sponge in it and is quiet.
