We have a 2007 Hummer H3 with the straight 5 engine in it. I have noticed the last few days that it seems like some of the power is gone and at the same time the fan (if you have an h3 you know what I'm talking about) in the engine compartment is even louder than usual. Any ideas? No lights on, no other issues with it.

 

check the fan clutch maybe it is seizing.

 

That would be my guess. It could be a more educated guess if we knew how many MILES are on the truck........ clutch fans do wear out eventually.