loud noise from fan, comes and goes, change fan 2 times what controls voltage to fan

The speed of the cooling fan on your 2005 GMC Envoy is controlled by the PowerTrain Control Module (PCM). That being said, it is not uncommon to find a broken wire in the harness from the fan clutch to the connector on the side of the fan shroud. If you are replacing just the fan clutch and not the harness a broken wire could be your problem. I have found that most aftermarket fan clutches for these vehicles don't come with the harness. The fan clutch available from A/C Delco may cost a little more but it comes with the short wire harness.

where are you buying your fan also if you still have a code it needs reset in order for the fan to work properly and if your buying your fan through gm that may be your problem the censor is on the front of the fan thats whats bad but you have to replace the entire unit go to advanced auto or auto zone and but a life time warrenty one not one of those reject gm fans