How do I intall a new fan belt on a 2004 envoy. I am not sure witch way it goes around the fan

If there is no diagram pasted in the engine compartment, check your owner's manual...or else go to your local auto store warehouse or Chevy dealership...usually the parts counter person can print out the diagram specifically to your vehicle. Since you did not mention the engine specs- I'm going to generically how to install a serpentine belt.

1.) make a loop and slip the loop around the crank shaft pulley
2.) continue looping the belt around the water pump pulley
3.) ...around the A/C pulley
4.) ...and around the idler pulley
Skip the alternator pulley for now- you want to do that one last.
5.) Continue placing the belt around the power steering pump pulley
6.) and over the belt tensioner pulley
7.) Now move the belt tensioner position so that you can loop the belt over the alternator.
8.) Now double check to make sure that the belt is properly and securely fastened around each pulley's grooves. Don't start the motor until you are absolutely sure... and can visually verify that the new belt is installed properly. And don't have anyone (or pets) standing around the car or open engine compartment when you initially start the car just in case the belt breaks...serious injuries can occur!
I've attached a generic drawing it may or may not fit the description of your auto.

If you have the Inline 6 (6 cylinder) ....watch the video below....it will have all of the info you need

Hope this is helpful

-Scott

How to Install Replace Engine Fan Serpentine Belt Chevy Trailblazer GMC...