Hitachi refrigerator works for 10 days and rests for one day

A Hitachi three-door refrigerator—left side freezer, right side regular fridge. Its issue, as shown in the pictures, is that after 10 days to two weeks (depending on the weather), it must be turned off for 24 hours because ice accumulates behind the refrigerator and the defrost heater does not work; I don't know why. I haven't attempted to fix it, and it's been working like this for over a year, thank God. Buy it as it is. The price is 550, negotiable. You just need a skilled technician; come and check its cooling performance yourself...