We had this continuous restart happen on our 2552. It happened right after I filled the fresh water tank to the top. While driving excess water sloshed out the overflow pipe and entered the furnace enclosure and caused the issue. I removed the fuse for the furnace to stop the restart. After awhile it dried out enough to reinsert the fuse and the furnace worked ok. I had this happen one more time and I took it back to Phoenix where they resealed around the enclosure and I haven’t had the problem reoccur. This repair was done almost two years ago.
I think the Atwood design makes it very susceptible to moisture. On my unit the control board is mounted at the bottom of the furnace enclosure meaning any water entering is probably going to make it to the electrical controls. I think the control board was relocated in later Atwood furnaces. A number of failures similar to mine were reported.
