Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove 1 connector from the right hand switch (pink leads)

Measurement:

Measure the resistance across the summer/winter switch (right hand with pink leads).
Test 1:
With the switch out (OFF position) - expect open circuit.
Test 2:
With the switch in (ON position) - expect short circuit.