Have RV Questions? Ask an RV Mechanic Online.
The first thing to check is if you are getting power TO the furnace. Do you have a removable panel over the exhaust and intake or not. Many newer units don't, and that limits the access to the control board. These newer control boards have been very unreliable and I never use them for that reason. The fan relay goes bad and won't turn on the motor. So check to be sure the fuse is good in the load center for the furnace and let me know about the access panel. IF you don't have one, the furnace has to be pulled out from the inside to get to the board and that is more work. Then the furnace can be bench tested while it is out and be sure everything is working properly. IF the board is the issue, I would go with an after market product made by Dinosaur Electronics as they are far superior to the OEM boards and have an outstanding warranty should you ever need it. Get back to me and let me know about the access and we can go from there. All follow ups are included in our fee. This may still be under warranty so keep that in mind as well.
The light may come on, but still not have over 12 VDC, so testing it with an actual meter would be best. About $20 or so at most hardware stores. You can remove the control board and take it into a shop to be tested. Have the receipt for your purchase if you think it is still under warranty. Even then, I would consider replacing it with a Dinosaur board just so you know it won't happen again. Take this out is time consuming in most cases.
I am adding a link to the Atwood manual which covers this model. Print it out so you have a copy. Great information in there. http://bryantrv.com/docs2/docs/hflamefurn04.pdf
Keep in mind that isn't always conclusive for some portions of the board, but it is for the fan relay. Get back to me if we need to dig deeper into this.