If a Dometic Single Zone LCD thermostat, I think it might be 5V DC. On a 2012, if this is for the living area A/C, I'd expect the thermostat wire to connect to a gray relay box just above the air return. I believe the power to that box starts at the main fuse box.
If checking fuses by looking for an illuminated LED in the fuse panel, that may be insufficient as the LEDs only illuminate when 1) the fuse is blown, AND 2) there's a load on the circuit. You may need to visually examine each fuse, and perhaps even check with the ohm function on a volt meter.