You sure that's not coming from the passenger side air vent itself? I had a similar rattle coming from the air vent, and went away when i had it replaced by the service center under warranty.

 

Yeah I thought its something from the vent aswell, I tried turning the fans off and even closing the vent on that right one. It feels like the sound is a bit muffled when it's closed. But the sound is still there even when fans turned off. Maybe some part that is loose