Hi Corndancer. Can you tell us what make and model furnace you have? Just curious.
It sounds to me that the unit is in lockout if it is trying but failing to light. This happens when a spark fails to light the burner. The blower will continue to run until the tstat is turned off and reset (in general).
Again- this is general to heaters. You need to find out why it is not igniting. Ron's suggestion about the propane is a good start. You can also begin to diagnose the DSI. The board works on a timer. It directs the blower to start, then it sends a current to open a gas valve and another current to produce a spark. It will either confirm a flame and you are good to go, or confirm no flame and try two more times to light after which it goes into lockout.
But, I really wouldn't go mucking about with the heater unless you are comfortable with this type of project. I see you have a 2013. Is it possible to take it to the dealers or to call them and have them walk you though some things?
DW, 3 Kids and our Goldens
2012 Shamrock 233S
2008 Toyota Sequoia 5.7L 4WD