Furnace runs on 12 Volt and will have a fuse; Fridge runs on 120 Volt for refrigeration and will have a breaker and 12 volt for the controls which has a fuse. And they are all at the converter panel.
Is this a new unit? Then I would assume there might be loose connections.
Be sure the switch on the Thermostat is in on position.
Check if you have 12 volt at the furnace connections. And check if you have 110 Volt and 12 Volt if you take the outside cover of the fridge unit where you can check it.
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