I'd suggest to remove the cover on the exhaust/inlet piping on the exterior of the Sunlite and vacuum out as much debris as possible. You can also push compressed air through those pipes. If you use air, open up the furnace and clean out all of the crud you blew into it and clean up the burner assembly.
I'm going to assume no one has serviced the furnace since new. If you aren't familiar with maintenance procedures, take the furnace to someone that is or call a mobile tech.
Another thing you could do is find the model number of the furnace and visit Chris Bryant's website (Bryant RV) and download the service manual for your furnace. Thanks Chris, for making these available!
The service manual has a trouble shooting chart and maintenance procedures outlined.