2006 Chevy Equinox AWD
Most common is the serpentine belt tensioner units, when they get weak they can have a rattling sound and it won't be long before they break, sometimes if you look at them while the engine is running you can actually see them chattering and a with mechanics steathascope you can hear them. Other problems could be power steering pumps and or cracked pulleys, even some internal engine componets can have a rattling noise, so I would get it checked quickly, this has the potential of leaving you stranded.
We had that with our 07 turned out to be the bearings in the alternator
Search Chevrolet Equinox Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Chevrolet Equinox Experts