The OP has a 2-way, but of interest to some, the 3-way's 12v element depends a lot on how much voltage it is getting for how many watts it can do.
It needs a minimum wattage to get any fridge cooling done. The usual RV with the fridge wires long and thin already makes for a voltage drop between fridge and 12v source such as the RV's battery. Add the long thin wires using the 7-pin and now your voltage drop is worse.
When I had my jury rig fridge cooling using the 12v element powered from an adjustable voltage converter plugged into shore power, I found there was a big voltage drop between the fridge's 12v connection behind the fridge to the wires from the battery and the connection to the circuit board where the 12v element goes on the terminals. Thin wires there too plus the path through the circuit board to the terminals the 12v element connects to. The element's own wires are thin.
That meant the 12v element still needed the converter's voltage to be higher to get any cooling done. The element needed about 200w to do a proper cool down like the 325w AC element would. If it was only getting 150w it would not do much at all. I had to set 15.2v on the converter (15.4v is the high limit for DC on the fridge)
So imagine how low the wattage must be on the 12v element doing it normally from the RV battery at 13.6v from converter or alternator.
That is why they keep saying the 12v element is just to maintain the fridge at a low temperature once it is already cooled down.
(I had the Kill-A-Watt meter to show the different wattages the converter was pulling to run the element at different voltage settings)
With some solar on the roof and a controller with adjustable voltage, you might do better with a 3-way on 12v by cranking up the controller voltage set points but keep it below 15.4v.
