Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4
Remove Lower Front Panel and Upper front Cover
Pull off the 3 wires on the APS
(noting the connection for correct reassembly)

Measurement:

Measure resistance between terminal 1(NC) and 3(C).
Reconnect wires correctly after measurement.