Wire unit (reference 1image "Cathode fan connections") of the Cathode Fan is disconnected.

Remove the left side cover of the projector and check the connection of the Cathode Fan.

Wire unit (reference 3 image "Cathode fan connections") of the fan units is disconnected from the Signal Backplane.

Remove the front cover and front dust filter from the projector and check if the wire unit (reference 3 image "Cathode fan connections") is inserted in the Signal Backplane.

Blocked Cathode Fan (reference 2 image "Cathode fan connections").

Check if the Cathode Fan is not blocked. Ensure that the Cathode Fan can turn freely.

Damaged wire unit.

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

Malfunction Fan Control board.

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

Cathode fan (reference 1 image "Cathode fan connections") end of life.

Replace the Cathode Fan. See "Lamp cathode fan".