The code is HYI and can be looked up
here .
I have been surprised to get 3 exchanges in the last 7 years to Highlands Inn including Thanksgiving and New Year. I suppose that is the offseason but it is one of our favorite places to be. As mentioned above it feels like a camp out in the woods yet you are minutes from Carmel and a few more minutes from Monterey and Big Sur.
While I haven't specifically searched recently I have never seen a great deal of availability but they do show up occasionally. One thing to keep in mind is that there are only a few 2 bedroom units so they are pretty much impossible to exchange into. Also check the room code to see if you get a loft 1-bedroom (which we like) or the single level which has just a sliding door to divide the room.