Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect high voltage plug from the fan
Disconnect connector X11 from the PCB

Measurement:

Check for continuity (zero resistance) between the ends of the brown and blue wires running from the fan to the left hand pins of connector X11.
Inspect the harness and connectors for good overall condition.