Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Volts Set meter to measure AC Volts
Gain access to the incoming connections at the PCB
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure the voltage between the FR pin at the external frost protection connector (turquoise) and the neutral on the incoming mains connector.
Is mains voltage measured?
Note:
The appearance and layout of the incoming mains connector can vary depending on the PCB version, utilise the appropriate neutral, the frost protection connector remains the same.