Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect X20 from the PCB
Disconnect the connector from the Fan
Disconnect the connector from the Fan
Measurement:
Measure the resistance of each wire in the Harness to the fan, the connections are as follows:
| Wire | Position in X20 |
| Red | 19 |
| White | 3 |
| Yellow | 4 |
| Blue | 20 |
Isolate as per TOPs P4
and refit as necessary