2004 Saturn Vue Clunking noise

Hello,
When I shift into reverse at slow speeds I hear a kind of "clunk clunk" noise. I had it checked out at Chevy, but they couldn't diagnose the problem.

Any idea's of what this could be? The only known problems I have is that the A/C does not work, and when turning the heater on, there is a hissing noise on the first two settings (not on high), and the washer fluid spray in front and rear. I think I am savvy enough to know that the washer fluid does not affect anything :)
Any idea's would be greatly appreciated!