Your RV's wiring colors might not match the colors that Atwood has on the heater. Ata least you have the correct model Suburban heater. Cut your wires on the Atwood so an inch or so of the original Atwood wire remains, so you can easily figure it out.
Do NOT do anything at your switch panel, just make the proper connections at the water heater.
The BLUE wire from the Atwood supplies the warning light, and the Suburban also uses BLUE for the light.
Now it gets confusing..........
The WHITE wire on the Atwood will connect to the ORANGE wire on the Suburban, to control the electric heat element.
The ORANGE wire on the Atwood will connect to the RED wire on the Suburban, to control the gas heat.
The GREEN wire on the Atwood will connect to ground, and if the Suburban has a Green or Black wire it uses for ground, connect to it.
If you have any issues, it will be the ground. I always carry the ground wire from the water heater back to the switch panel, but most manufacturers will not, it involves another wire, so they drop to the nearest ground.
I really need to start collecting these discarded Atwood units and rebuilding them. There is nothing on them that cannot be repaired or replaced, and I feel that they are a better heater than the Suburban.
Charles
