It is a simple process if the 2004 is the same as earlier years and I would see no reason for it to change. It is a single microV serpentine belt. Draw a diagram of the path of the existing belt. Buy a new belt using the PN for your coach and compare it for length and width, for mine that PN is Dayco PN 20-9612 or a Magnum 0206319. I attached a photo of the tensioner. At the bottom there is a 1/2 square hole for a 1/2 inch drive breaker bar or long handled 1/2 drive wrench. You use that to take the tension off of the belt and remove it and gently let the tensioner move until it rests on a stop, While the belt is off rotate all the idle and tensioner pulleys and feel for smooth operation and no play. Replace any that have issues. Move the tensioner just as you did before and slip on the new belt. Check the path and if all is well start the engine and check it for smooth operation.
This is a very simple do it yourself project that any mechanic is well familiar with. No real worry about doing it right if the proper belt is used.
Later Ed
