Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect the wires from the condense pressure switch
Measurement:
Measure the resistance between terminal 1 and
terminal 2 on the condense pressure switch.
Expected resistance short circuit.
Note:
White wire connects to terminal 1
Black wire connects to terminal 2
terminal 2 on the condense pressure switch.
Expected resistance short circuit.
Note:
White wire connects to terminal 1
Black wire connects to terminal 2
Isolate as per TOPs P4
and refit as necessary