1. The Auto Temps refers, moving the Slider up and down only changes the lower temp a max of about 4 degrees
2. Even if you have a 3 way refer, operating on 12 volts is ONLY for when the unit is in Transit and your Chassis engine Alternator is supplying the needed voltage/amps to power the 12 volt element. It is NOT designed to operate on a Power Converter, as it takes a lot of power to run that 12 volt element.
3. Dometic refers have 2 sleeves for Heat elements. IF you have a LP/120 ONLY and the 120 element is frozen in place, you install a new element in the unused sleeve. If you have a 3 way, it is best to remove the 12 element if it will come out and install a new 120 in that sleeve.
4. Trying to remove a rusted/frozen element can result in detaching the sleeve weld from the flue tube and either causing a leak or the slightly detached sleeve will NOT transmit the required heat to the flue tube. Doug