Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to DC Volts Set meter to measure DC Volts
CH Demand
Hinge down the PCB housing
Position PCB as illustrated in image
Disconnect fan connector at the fan and make safe
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Test 1:
Measure for DC volts across the white wire of illustrated connector to a suitable neutral.
Expected voltage approx. 13.4V DC.
Test 2:
Measure for DC volts across the green wire of illustrated connector to a suitable neutral.
Expected voltage approx. 0V DC.