Tried my heater in my camper before i take it to hunting camp and have problem. The heater blows but its cold air. you can here something clicking but its not lighting.
Two things might be happening. You might be out of propane and the furnace is trying to ignite but can't because it is getting no fuel. Second, the batteries might be too weak to ignite the propane. I would bet on the first one. If that's not the case, then I am not smart enough to try to give you more help.