I bought a 2000 TL used and have a clunking noise coming from behind the radio/climate control area. It happens whenever I turn and I can make it happen constantly by swerving back and forth down the road. My first thought was that someone previously stuck something in one of the vents and it worked its way down to the bottom where it is now rolling around and clunking when it rolls and hits the left or right side. But, it sounds large, like the size of a golf ball. Not something small enough to fit through the vents like a pencil or marble. It drives me nuts when I'm driving on a curvy road. I have pulled the radio and center console out and there is nothing back there loose. It seems like it is inside the ventilation system. Has anybody else heard of this problem?

 

have you removed the cabin air filter to see if there is anything loose in there?