I believe all the rooms on the Spirit have small refrigerators, our balcony cabin did - however- they are stocked mini bars. If you want to use it for your own stuff - like, water, sodas, medicine that needs to be refrigerated etc... take the mini-bar items out and leave them in plain view on the counter above so that you aren't charged for them.
The prices for the items in the fridge add up to no more than you would pay anywhere else (I thought, anyway). I munched on the macadamia nuts one night and I think they were only 4 dollars. (Sounds like a lot for a small jar of nuts, huh?) But - hey - it's vacation - lol!!
I thought it was a nice convenience to be able to grab a quick snack or can of soda. There were candy bars, nuts, pringles, little bottles of liquor etc...
As soon as an item is used, it's charged to your account and promptly replaced.
This is why I say if you are not going to comsume what's stocked, leave it in plain sight so you don't get charged. I did this and put my own bottled water in there, as well as the medication I am on that I inject myself with that needs to be kept in the fridge at all times.
You need to ask your cabin steward to unlock the fridge for you , so leave a note as soon as you get to your room, or put in a call to him/her to have them unlock it.
Sorry to be so long winded- hope this helps?