I need some help. For as long as i can remember whenever I stomp the gas then let off, or when I go over bumps, I hear a rattling that sounds like a metal ball in a can, like a really hollow metal clanging. The reason i post this in the A/C section is because ~2 years ago when i had the car in the shop my mechanic said that the compressor was going out and was making a rattling. How viable is that, and, what would be the most likely culprit? Or is it something different? The only others causes i can think of are the exhaust pipes or maybe the brakes? Though I really have no idea whether or not drum and/or disc brakes can rattle. Any advice would be greatly appreciated. Thanks!