Set Appliance State:

Mains Power Off
Set Multimeter to AC Volts Set meter to measure AC Volts
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure for mains voltage across pin 4 (brown) of connector CN302 (fan live) and a suitable earth connection.
Is mains voltage present?