I pulled the heater ducts off the back of the heater their seems to be sufficient air flow I turned the heater on and the burner kept going off and on I am wondering if it is a propane problemdigger1
I'm not familiar w/that model - 315rst. Typo for 317RST?
It sounds like the ductwork off the furnace may have come loose.
If it's a fifth wheel, you may be able to check it by pulling off the back wall in your pass-thru storage compartment
or by pulling out a cabinet drawer inside that may be located near your furnace.
Just guessing here......
When I turn my heater on it makes a lot of noise and not hot air is coming out of the vents . burner is cycling on and off blowing hot air out of the vent on the outside.