I checked temperature compensation chart . If you know/find type of probe /thermistor , download ohms to temp chart ,if you mock the temp with resistor or rehostat for 30f it puts it right on line with those voltages on AGM setting.
You could also use resistor in series to add ohms or parallel to subtract resistance ,to compensate default setting without probe at 70f to mock 30f. So 70f=30f To still use probe .There are resistor plugin spread sheet calculator.
I let think about and do more investigating before spending more time to help you may not want.
They sell similar device for LP fridge made with rheostat,instead of moving around thermistor.
95 Monaco Crown Royale
M11 400hp, 4060 trans.
Aquahot, Generac Guardian7.5k