Viewsonic projector will make a noise from the fan when the fan cools the projector down. But if it has loud noise, you can check as follows.
1. Fan Obstruction
If it seems like there is something hitting the fan blades it could mean that there is an obstruction in contact with the fan blades. You can try to identify the obstruction visually then try shaking it out if possible.
2. Turn off the projector for a while
If the projector is overheating, your projector may need to power it off to help it cool down. If the loud noise persists, it is strongly recommended that the unit be sent in for service.
