Set Appliance State:

Mains Power Off
Set Multimeter to AC Volts Set meter to measure AC Volts
NO demands
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure the AC voltage between the Live (Brown) and Neutral (Blue) wires at the fan AC connector (3 wire)
Expect mains voltage.