Sounds like you need to have a tech look at it. Meanwhile go to Walmart or some store like that and purchase an electric space heater. We have one that in really cold times we set up by the drivers seat and it blows heated air back through the coach. Course it won't make it toasty, but it sure helps. Then lots of blankets.
Are you sure you have propane in the tank? Have you checked fuses? Ours are just under the frig, not sure where yours would be. Make sure the air intake for the furnace is clear.
Just some simple things, but probably you need a tech.
Jim and Carol Cooper with Oreo the Kitty
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2002 Journey, Cat 330, 2015 Ford Explorer Blue Ox, AF1