Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect leads from fan (take care not to damage spades)

Measurement:

Test 1:
Measure the resistance between the two fan spade connectors.
Resistance should be approximately 30 - 85Ω.
Test 2:
Measure the resistance between one of the fan spade connectors to a suitable earth point.
Resistance should be greater than 1MΩ (or O.L).