RESISTANCE AIR PRESSURE SWITCH AT REST

Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4

Set Multimeter to Resistance

Remove the wires from the air pressure switch noting their locations

Measurement:

Measure the resistance between common and normally closed terminals on the APS (terminals 1 and 2)
Expect continuity/zero resistance.
Is the resistance as expected?

Note:
APS is shown removed for clarity but test is carried out with APS in situ with the air pressure tube connected.