Problem

The channels to the side vents are loose.

Remove the gloveboxes on both sides (glovebox and map pocket).

Blow/vacuum the inside of the ducts.

Where the air is coming out from the ventilation system:
Remove the plastic cups, squeeze/twist the channels firmly into these and put them back in place. NOTE! They must be put down at a specific angle so that they lock into place.

Then squeeze/twist the other end of the channels firmly in place.

Install the glovebox and map pocket again.

Detached channel.

Plastic cup. These must be removed so that you can get the channel firmly in place.

Here the channel is connected to the cup.