My admial keeps getting warm

Question

hi i have the amiral model AD222.the thing is in the freezer department half way down the back wall gets white frost on it and the freezer and fride start to get warm.so i turn it of for 48 hrs and theres a lot of water under it in the drip tray.then when i turn it back on again its fine works ok then 4 wks later i have the same prob have to turn it of.once a month can u help me thanks diane