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 "Remove and clean the front dust filter".

Malfunction SMPS module

Replace the SMPS module. See "Replacement of the SMPS board".

Malfunction Fan Control board.

Replace the Fan Control board. See "Replacement of a Card Cage board".