Refrigeration Experts Help

[Tropic1]

I have a separate compressor and a cold plate in my freezer. I use my boat about 6 months and store about 6 months. When I get to my boat and turn on the system everything works well for about 3 months when I have to defrost the freezer. When I restart the freezer it runs good for a while then it starts using about 1.5 amps at startup and the line running from the compressor to the cold plate freezes up during startup and then defrosts after about a minute of running and the electric consumption starts to go back down to near normal usage. Not sure what happens after the defrost but wondering what causes the freezing of the line between the compressor and cold plate? Any refrigeration experts have an idea? Thanks, Dave