I just managed to find enough time to listen to the podcast of this weeks show. Right off the bat there was a question about an Ion. I perked right up since I own the same type of car.
Anyway, long story short, I believe the noise the caller heard (she described it as an agitated cow) is in fact the clutch for the a/c and is likely somewhat unrelated to the lack of cold air. My car makes the exact same noise. The noise is the a/c clutch disengaging when you rev the engine up above about 4.5k rpm while the compressor is under load.
I took it to the dealer they said the noise is not at all uncommon and that there really wasn’t much to worry about, and since it’s not under warranty anymore I didn’t really push the issue since it still works fine.
Don’t know that this information would matter too much to the caller, but I just thought I’d toss in my 2?.