Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Unplug the 3 wire plug from the fan

Measurement:

Measure for continuity (zero resistance) between the ends of the brown and blue wires, in turn, at connector X11 on the PCB to the brown and blue wires of the disconnected plug.
Inspect the harness and connectors for good overall condition.