Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove control box cover
Disconnect plug marked CN15

Measurement:

Test 1:
Set CH temperature selector to maximum
Measure the resistance across the red wire (connection 6) and the black wire (connection 5).
Resistance measured should be approximately 10.6 kOhms.

Turn CH temperature selector to minimum.
Resistance should reduce to under 100 Ohms.
Test 2:
Set CH temperature selector to minimum
Measure the resistance across the white wire (connection 4) and the black wire (connection 5).
Resistance measured should be approximately 10.6 kOhms.

Turn CH temperature selector to maximum.
Resistance should reduce to under 100 Ohms.