Set Appliance State:

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

Measurement:

Measure the AC voltage between the live and neutral wires on the 3 wire fan connector to the fan assembly.
Expect mains voltage (approximately 240v)
Is the voltage measured as expected?