faint bearing noise, glovebox area

2013 Prius v. We have recently noticed a faint noise coming from the front passenger, glove box area. It's similar to the sound of a failing fan bearing in a computer tower. I removed everything from the glove box, cleaned some leaves from the trough under the windshield wipers, and removed some small stones from the front/right wheel cover, but the noise persists. There appears to be a fan to the right of the cabin air filter. Further investigation required as passenger.

First post. This car has been virtually maintenance free for 75,000 miles. About 45 mpg, as advertised. My only complaint is that the seats are designed for smaller peoples.

 

OOps. Blower is below cabin air filter.
I took a test drive Sunday and Monday. I removed a sunflower seed from passenger beverage rack. I opened glove box and removed the cabin air filter and manuals, etc. The rattle starts about 30 mph, even with the blower "off." There is no rattle while stopped with the fan at various speeds.

A-Ha. I have had the oil changed several times at a local oil change garage. The Toyota-trained supervisor told me that the cover to the cabin air filter was missing. I had no idea what it looked like. I didn't investigate further until today when I was searching for the cause of my rattle. When I removed the lower glove box door, the cover was resting on some wire harnesses below the glove box door.

I reassembled the glove box and drove again Tuesday. My rattle has disappeared.

 

Unfortunately, my noise didn't really disappear. It must have been wishful thinking.
So, when we took the V to a dealer in Phoenix last week to install a software recall upgrade, we asked them to check for that faint noise. They performed an all-around inspection before they drove it to listen for the noise. The tech reported that he heard no noise during the test drive. So, we accompanied the tech on another test drive. Nothing. Then the tech told us that he had tightened some fasteners underneath near the oil filter and oil drain plug.
There are some thin plastic panels under the V which probably improve air flow and reduce wind resistance at highway speeds. The panels are held in place by plastic "rivets." If a rivet was loose, the corner of the flimsy plastic panel was probably vibrating against an adjacent panel at speeds over 30 MPH. We didn't hear the noise a 75 MPH on the drive home.
And that's the rest of the story