Found a breaker that might be a good place to start.
I cut a couple items of the drawings for you to see a bit of what I'm looking at.
These come from this drawing:
https://www.winnebago.com/Files/File...ire_163620.pdf
The breaker drawing is on sheet two near the top left. The drawing from thermostat to furnace is on this drawing and seems to be the same for this part, whether with or without heat pump:
https://www.winnebago.com/Files/File...ire_138913.pdf
Clicking these snips may get you a better/larger view but what I see is that wire JB is power from the breaker to furnace, so a check of that specific breaker is needed to make sure power is headed the right place. I'm not sure if this view is from the front or looking from the back, though so make sure both left bottom as well as bottom right breaker if they are not labeled. ????
But if you get into it that far and have to open the furnace to look at wires there as shown on the other snip, blue wire on pin two at the connector is ground, yellow wire is 12 v negative and red wire positive 12vDC.
Or you might also check those at the thermostat if it is handier??
Maybe do a bit of checking for the correct voltages and ground?