An RV furnace is really just a series of switch's. Find the switch that won't turn on and you've solved the problem. However, getting access to that switch is the problem.
Hydroflame furnace's have access to its operation from the outside. This allows for a relatively quick repair.
Suburban furnace's do not. This design difference means that some inside work must done to gain access to the furnace.
If you've had issue with your furnace contact me. I can help.