Thanks for your comment.
The huts "opening and closing" times are often subjected to conditions, i.e. snow conditions.
As most of the huts in the Jotunheim are privately owned, you will need to check each website for the opening and closing times. They can be found at https://www.ut.no.
As most huts are run at a local level its best to check in the shoulder seasons if they are open.
After slogging our guts out through sleet to the top of Fannaråken Hytta, we found it not only locked but hermetically sealed for the winter. When I raised the matter with DNT, they said.... Sorry about that.
Post edited at 13:49