Ambient temperature too high.

Check the ambient temperature at the air inlets of the projector. Make sure that the ambient temperature does not exceed 35°C (95°F).

Blocked front filter.

Clean the filter at the front side of the projector or replace with a new one. See "Cleaning the front dust filter".

Malfunction SMPS module

Replace the SMPS module.

Malfunction Fan Control board.

Replace the Fan Control board. See "Removing a board in the card cage".