Terry, when I replaced that line from the solenoid to the top, I left the heat wires disconnected. Those are to protect the line from freezing but it seems to be on constantly. Unless that thermal switch in my unit is bad?? In our situation we don't winterize and are rarely exposed to extreme temperatures. I believe this help extend the life of that tubing.
While on the subject, I tried with no luck, to find something to use in place of that clear tube. The clear nylon/poly stuff in the home centers states not for potable water or ice makers. Not sure why, must have something to do with the chemical make-up of the tubing. The fitting out the "out" side of the solenoid is not like anything I've ever seen before. I guess for now, we're stuck with the Dometic supplied tube.