ah. just found the owner's manual. it's model #MCBR1000W
Okay. I removed everything from the freezer, and at the bottom right corner there was frost build up, right where the panel can be removed. So I unscrewed the panel. Try as I might, I can't seem to pry off the panel completely. Only the top section is loose. So I can't really see what's going on in there, but you were right about the frost. Also, I don't feel any air coming through the vent in the fridge section.
Should I wait until it's had a chance to thaw out before trying to pry the back panel of the freezer off? I pulled so hard I cracked the lower portion of the panel.