I'm not sure if they're called bleeder valves, but there is one right by the radiator pressure cap and one in front of the air filter box.

I'm talking about the little black plastic things you can tighten and loosen with your fingers, but I don't think they come off.

Are they supposed to be tightened and closed or left open?

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2007 Jeep Liberty Sport
Not Just Red..............Inferno Red !
Automatic, 4WD
Mopar Skids, Tow Hooks

My guess is these are the caps on the air conditioner service ports.

Leave them tight to keep them clean and to help if the schrader valves there leak a little.