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.
I do what PATH1 says before firing up my furnace for the first time after getting setup at the campground. Lightning the stove burners purges the propane lines...
I always turn-off my propane tanks when in travel mode so this catches me for forgetting to turn on my propane before using it hehe...