Wire of the Lamp Cathode Fan is disconnected.

Remove the Lamp House and Lamp Cathode fan (reference 1 image) and check the connection of the Lamp Cathode Fan (reference 3 image).

Wire of the rear fan units is disconnected from the Signal Backplane.

Remove the Lamp House and Lamp Cathode fan and check if the wire unit (reference 2 image) is inserted in the Signal Backplane.

Blocked Lamp Cathode Fan.

Check if the Cathode Fan is not blocked. Ensure that the Cathode Fan can turn freely (reference 1 image).

Damaged wire.

Check if the wire of the Cathode Fan is not damaged. Repair if possible, otherwise replace with new one.

Lamp Cathode Fan end of life.

Replace the Lamp Cathode Fan. See service manual chapter "Replacement of the Lamp Cathode Fan".

Malfunction Cinema Controller.

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