Lexus Rx450h SUV... rattles only when cold



2010 Lexus Rx450h… Rattles in the morning, only when really cold. (Around freezing?).
Somewhere in or near the passenger side door, or the air vent by that door.
It gets quiet(er) after warmup.
Car has been at the dealer for a week… They can’t find it; they want to pack in additional insulation. That hardly sounds like a sound solution. (Oh, sorry!)
Any help most appreciated.


Sounds like a heat shield coming loose.



Or move to SoCal or SoFla.