Other fans have also low speed warnings/errors.

Check for errors/warnings related to the +24V of the SMPS.

Blocked fan.

Check if the fan can turn freely (reference 1 image)

Note: The left fan of the engine is the located on the lower-left side of the heat exchanger seen from the Light Processor compartment side. The wire of the left fan is marked with an orange cable tie.

Fan disconnected.

Check fan wire connections (reference 11 image) on top of the Light Processor compartment and on the signal backplane (reference 20 image)

Damaged wire.

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

Fan end of live.

Replace the fan. See service procedure "Replacement of the Small Air Dryer fan".

Malfunction CCB.

Replace the CCB, see service procedure "Replacement of the Cinema Controller".