What the ___ is that sound? It just started yesterday...

It has to be under the hood, because there is nothing loose on the outside or under-carriage of the car. I am inclined to start pulling the little rubber flaps off of the back side of the radiator to see if they're the cause.

 

OK, so I did some troubleshooting. It is not the rubber flaps on the fan shroud making that noise. And the speed is closer to 55 than 50
- It almost sounds like it could be coming form the air box (ducting) between the cabin and exterior (for fresh air).
- But... It's possible that something in the sun roof area is flapping when the roof is closed.???? I am at a loss... Any thoughts...

 

Can you record the sound?

 

Is part if the splash pan broke?

 

It's not the splash pan, the pan was completely removed before I received the car.

 

Still playing the "what is that sound?" game. You know the game, the one where you drive down the road sitting halfway in the passenger seat. Trying to narrow down the source of a noise that only occurrs at fifty miles per hour.

The good news is that I have narrowed it down to being in the cabin, under the dash, not under the hood. It's starting to sound like a little motor with a stripped plastic gear. It seems to be comming from the A/C air ducting, but nothing I do with the A/C controls has any affect.

I also have the A/C bellows hiss that seems common in the S90.

Any assistance would be greatly appreciated,
Mac