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
Mains Reset Switch OFF
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Mains reset switch ON.
Measure voltage across pin 1 of fan connector and a suitable earth point.
Expected voltage approximately 27 - 38 volts DC.
Note.
1. Ensure a good electrical connection is made at fan connector or misdiagnosis will occur.
2. Harness colours may change but test points will remain the same.