Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Volts Set meter to measure AC Volts
Turn Hot Water Tap On
Use Insulation Mat as required
Selector switch set to CH/DHW position
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Allow the fan to run.
Test 1.
Measure the AC voltage between pin 3 blue (Neutral) on connector CN1
(black probe) and pin 2 (blue) on connector CN6.
Test 2.
Measure the AC voltage between pin 3 blue (Neutral) on connector CN1
(black probe) and pin 1 (brown) on connector CN6.
On both tests expect voltage of between approximately 55 - 70 Vac
for a period of 5 seconds.