Is there 120-volt A/C power to the refrigerator power outlet?
If yes, turn the refrigerator on. A volt ohm meter can check for 120 VAC at the heating element.
If yes, it's the gas portion of the refrigerator.
Does your refrigerator not light or stay lit on gas?
Do you hear the valve click open, smell gas, but don’t hear or see a spark?
Do you hear a spark, but no gas valve "click"?
Does the gas valve click and igniter spark, but the burner doesn’t ignite? Or flame is weak?
Does the refrigerator light on gas, but won’t stay lit?
Any of those problems could be caused by:
A dirty or bad igniter or thermocouple
Bad circuit board
Gas valve has failed
Low gas pressure
Your venting or cooling unit is probably the issue.
Look for loose insulation, jammed leaves, needles, or bird nests on the roof vent.
If you see these dangerous signs of a failed cooling unit, shut off your refrigerator and call an expert:
Yellow stains on cooling unit.
A strong ammonia smell in the freezer or refrigerator