Set Appliance State:

Mains Power Off
Ensure NO demands
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

1) With NO demand does the fan run continuously?
Set temperature control to MAX and apply a CH demand:
2) With a CH demand does the fan run?
Note:
The appliance may take about 12 seconds for the fan to run.