Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector X2 from the PCB
Remove the DC fan connector from the fan assembly

Measurement:

Measure the resistance of each of the wires in the fan harness as listed below:
Pin 3 on connector X2 to the black wire on the fan connector.
Pin 7 on connector X2 to the grey wire on the fan connector.
Pin 12 on connector X2 to the blue wire on the fan connector.
Pin 17 on connector X2 to the red wire on the fan connector.
Expect continuity / zero resistance on each wire.
Also visually inspect the condition of the harness.
Are the resistances measured as expected and is the harness in good condition?