Have you checked to see if the burner is lit? If it is like the one in my '74. You must select either gas or electric, then set the thermostat (separate for each)
I have to light ours initially from the outside access door. Then most of the time, not always, I can light it from inside.
Check for evidence of yellow dust or the smell of ammonia when looking thru the outside hatch. If either exists. Get out your wallet. Time for a new refer.
If it is the original model. There is no 12 volt
DC involved. It is either gas or 120 volts AC.