I am agreeing with Phillip but would like to add the service manual procedure for your H3. It will also help us if you let us know what engine size your H3 is.
"DRIVE BELT SQUEAL DIAGNOSIS
A loose or improper installation of a body component, a suspension component, or other items of the vehicle may cause the squeal noise.
If the noise is intermittent, verify the accessory drive components by varying their loads making sure they are operated to their maximum capacity. An overcharged A/C system, power steering system with a pinched hose or wrong fluid, or a generator failing are suggested items to inspect.
2: The noise may not be engine related. This step is to verify that the engine is making the noise. If the engine is not making the noise do not proceed further.
3: The noise may be an internal engine noise. Removing the drive belt and operating the engine for a brief period will verify the squeal noise is the drive belts or an accessory drive component. When removing the drive belt the water pump may not be operating and the
engine may overheat. Also DTCs may set when the engine is operating with the drive belt removed.
4: This test is to verify that an accessory drive component does not have a seized bearing. With the belt remove test the bearings in the accessory drive components for turning smoothly. Also test the accessory drive components with the engine operating by varying the
load on the components to verify that the components operate properly.
5: This test is to verify that the drive belt tensioner operates properly. If the drive belt tensioner is not operating properly, proper belt tension may not be achieved to keep the drive belt from slipping which could cause a squeal noise.
6: This test is to verify that the drive belts is not too long, which would prevent the drive belt tensioner from working properly. Also if an incorrect length drive belt was installed, it may not be routed properly and may be turning an accessory drive component in the wrong direction.
7: Misalignment of the pulleys may be caused from improper mounting of the accessory drive component, incorrect installation of the accessory drive component pulley, or the pulley bent inward or outward from a previous repair. Test for a misalign pulley using a
straight edge in the pulley grooves across two or three pulleys. If a misalign pulley is found refer to that accessory drive component for the proper installation procedure for that pulley.
8: This test is to verify that the pulleys are the correct diameter or width. Using a known good vehicle compare the pulley sizes." Again, this is from the GM service manual and even so it recommends to do something,I'd be cautious running it without the belt for to long:-)
I hope this will help a bit. Once you can give us your engine size and are for certain that your pulley needs to be changed, let us know so we can get you the right information.