2003 jayco granite ridge refrigerator problems

Out of level can make a difference in whether a unit runs, BUT if it runs when the engine is running, but not when the engine is off the next question becomes 12 volt power.
Have you checked the house battery/batteries?
Are they charged? Are they there? if you just bought it, do you know?
Do the interior lights all function when the engine is not running?
Time to get a volt meter and start checking.