Field type chanfe from Text to Code (Nav2009 to Nav2013)

hi everyone,

I have merged tables from 2009 and 2013 versions. After that, I'm trying to import those objects to a database converted from 2009 to 2013, but it's not possible, because there are some fields (ex: table 15:G/L Account, field: No.), that in 2009 where Text type, and in 2013 code type, and can't be replaced, because they already have data on the related database.
How can this be solved? Do I forget any step in the conversion?

Thanks for your help!