Wire unit (reference 2 image) disconnected from the Signal Backplane.

Remove the Card Cage cover from the projector and check if the wire unit (reference 2 image) is inserted in the Signal Backplane.

Blocked fan (reference 1 image).

Remove the Fan Control board and look inside the compartment to check if the fan is not blocked. Unblock the fan. Ensure that the fan can turn freely.

Damaged wire unit.

Remove the Fan Control board and look inside the compartment to check the wire unit of the ICP fan.. Repair if possible, otherwise replace with new one.

Malfunction Fan Control board.

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

Fan end of life.

Replace the fan. See service manual chapter "Replacement of the ICP fan".