My h2 started making a funny knocking noice over by the pass. Side. When i turned it on this morning. Never heard this noice before drove for about half hr and the noice didn't stop. Turned off the ac to see if it has something to do with it noise still there turn off the hummer noise goes away turn it back on noise starts again fml can anyone help me plz.

 

NOISE ! Check exhaust manifolds:

 

Not exhaust maniford its inside the truck knocking sound around the dash

 

Probably have a blend door actuator going bad.

 

MOVED to the H2 sections where ALL H2 Tech Questions belong. Crazy how that works...............

Off Topic is for like talking about your favorite rocking chair and swiss cheese, ie. nothing to do with any Hummer.