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 "Check the front dust filter".

Malfunction SMPS module

Replace the SMPS module, see "Replacement of the Switched Mode Power Supply".

Malfunction Fan Control board.

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