You'd think at the price of these vehicles that they would not fall apart AT ALL.....Or fix every little things that breaks before the 10 year of age mark.

Sounds like someone is boiling water rapidly inside the dash and it knocks too. I mentioned it when I carried it in for service and they said they didn't hear anything. Of course it doesn't do it right off it so they looked at me as if I was a nut, they knew very well that other people was complaining but who cares it wasn't their car doing that.

Knocking noise in dash, actually the relay/valve near the front floor vent is defective, only cure I found was to replace it. Chevy was no help.

Ever since I bought the truck with 15,000 miles on it, it has had a knocking/rattling sound come from the dash. The instrument panel cluster has been replaced twice for this. After the extended warranty expired, the rattling/knocking sound came back. There may have been a combined total of 10,000 miles when the dash did not rattle, knock, or make some other noise.