I bought a 2006 certified LS430 yesterday with ventilated/heated seats and I've noticed that very little air comes through the seats, and it appears to be the temp of the cabin air. I've eliminated the air filters as the culprit, so I think its what others have posted here: its just not gonna be air conditioned air. I suppose that's why Lexus refers to them as ventilated rather than cooled seats. Regardless, its a great car. I had no idea I "needed" radar cruise control, but after driving from Fort Worth back to Houston I'm spoiled! I traded in my 1998 LS400 which I thought was a quiet car. Compared to this one it was like driving with the top down.
I read the manual about replacing the seat air filters. My thougths after reading: "Huh?" After finding instructions on how to check the seat air filters on this site I joined. Thanks to those of you who posted the how to.