Set Appliance State:
Set Multimeter to AC Volts 
Isolate Mains Power to appliance as per TOPs P4
Remove the connector from the fan and make safe
NO demand
Remove the connector from the fan and make safe
NO demand
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Ensure both DHW and CH at the external timer are turned OFF before continuing.
Measure the AC voltage between each of the 5 wires to the fan at the PCB and a suitable earth point
Voltages should be approximately as below:
Measure the AC voltage between each of the 5 wires to the fan at the PCB and a suitable earth point
Voltages should be approximately as below:
| Wire | Voltage (AC) |
| Yellow | 130 |
| Black | 130 |
| Red | 130 |
| White | 130 |
| Blue | 20 |
Isolate as per TOPs P4
and refit as necessary