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 dust filter.

Clean the large dust filter or replace with new one. See service manual chapter "Dust Filters".

Defect temperature sensor.

Replace the ambient temperature sensor (reference 12 image).

Malfunction Cinema Control board.

Replace the Cinema Control board. See service manual chapter "Replacement of the Cinema Controller".