Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect leads at the common (C) and normally closed (N/C) terminals on the air pressure switch
Measurement:
Measure the resistance between the common and
normally closed terminals on the air pressure switch.
Expected resistance short circuit (zero resistance).
Note:
Design of APS may differ, refer to information on APS
to ensure you are testing across correct terminals.
normally closed terminals on the air pressure switch.
Expected resistance short circuit (zero resistance).
Note:
Design of APS may differ, refer to information on APS
to ensure you are testing across correct terminals.
Isolate as per TOPs P4
and refit as necessary