Most fridges work using a "trickle down " effect whereby there is only 1 cooling coil, and it directly feeds the freezer. The cool air falls down into the fridge area, cooling it.
If you remove any shrouding/door from around the freezer area, then the fridge part will cool quicker, and the compressor won't run as much.
I did this w/ an old fridge I use for beer storage which was freezing up. W/o the freezer area shrouded, it doesn't freeze up there anymore, although I do use a temp controller to keep the fridge area at a set temp.