Rattle in dash-finally found and fixed it!

I have a 2008 Prius Touring model that I bought new in April of 2008. I developed a rattle in the dash that I've chased for over 5 1/2 years now and finally found and fixed it. The noise was coming from the left corner at about the area of the little vent for the small triangular window. It would come and go over the years but seemed louder and more offensive lately so I decided to tear into the dash again for the umteenth time. Well I finally isolated it in the area of the silver ac/heater vent unit at the left side of the dash. It's the silver thing with the round barrel knob to operate the flapper that controls air flow. If you grab it at the top and bottom and pull and wiggle it towards you it'll pop straight out. Once out, check the little plastic arms that the barrel knob controls. It's a two piece black plastic thing with a pivot point and that is exactly what is rattling! I put some very heavy gummy and sticky silicone grease on this point and the rattle is now gone. I'm thinking this is a common problem and thought I read about others complaining of the same thing. Hope this info helps. I was almost ready to sell this car to avoid the nuisance unnerving rattling.

 

agrahul11.
Here is a picture of the area in question which is the left side heater/ac vent assembly at the upper left hand side of the dash. The picture is sideways but if you look carefully, you'll see the round black knob on the bottom and as you rotate it, it'll control the amount of air coming out of the vent. Once you remove this silver vent assembly from the dash by grabbing the top and bottom and wiggling it while pulling straight out, you'll see that as you rotate the above mentioned round black knob, a plastic arm is connected to it and also is connected to another black plastic arm. It's this connection that I found was rattling. What to do? Couldn't glue it together nor immobilize it so I elected to put some very heavy, sticky CarQuest Silicone Brake Lubricant at this juncture and all was well after that. I must admit that this noise wasn't necessarily always present prior to the fix and occasionally it still sounds like it wants to start up a bit but after I rotate the round black knob again, the noise is gone for a very long while. Good luck with the fix.