Refrigerator side want stay cold

Question

i have a stainless steel side by side refrigerator the freezer will get doen to 15 below o and hold it but the refrigerator side gets down to 39 and quits cooling untill it gets back up to about 65.
also sometimes when i open the refrigerator the deep freez and the refrigerator controle light stays out untill i toggle the door switch but the inside light comes right on