While I don't have a trailer of your vintage you may find that your furnace is fused in two places. One is the 12 volt fuse panel, the other may be an inline fuse within the furnace itself. In my Safari my fuse panel is behind the front couch on the wall below the window. My inline fuse is accessed from the outside furnace cover and behind the fiberboard cover.
Another possiblity is the fact that your thermostat is inoperable.
Jack
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Jack Canavera
STL Mo. AIR #56 S/OS#15
'04 Classic 30' S.O.,'03 GMC Savana 2500
In a 1974, the 12v fuse is under the sink, next to the furnace. They may be more, we forgot. It could be well hidden in a tangle of wires (in ours, it's a mess, the wires have plenty of extra length).
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