There are some possible reasons caused, please check below first:
<Airflow>
Air Flow is important for cooling:
- Please make sure the intake and exhaust vents are free from obstruction.
- Make sure the projector is not enclosed or right against a wall - it needs ventilation space.
- Don’t place the projector on top of other electronic equipment, such as an AV receiver.
<High Altitude>
If the projector is being used in higher altitude you will need to turn on the “High Altitude” mode. The fan will thus operate at a higher speed to intake more air. Please check user guide to enable it.
If above steps don’t help, please contact ViewSonic service center.