Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove fan connector from the PCB

Measurement:

Test 1:
Measure the resistance between pin 1 (red) and
pin 3 (blue) on the fan connector.
Expected resistance between 110 - 130 Ohms.
Test 2:
Measure between pin 1 (red) and a suitable earth.
Expect a resistance of 1 MOhm or greater.