Sub Zero 550

Question

You gave me a suggestion for water freezing up when it ran acroos the pull out rail to blow the drain line out. It was not clogged when i poured water through this and within a week froze up again.

There is a small piece of metal that appears to attach to a heater coil then leads into the drain tube should this be there?

Still has the same problem of freezing up any other suggestions would be appreciated.