I like them on each shelf level because the temps can vary significantly. To keep some food the longest I have to keep it 33 to 37 degrees. Coldest on top and warmest on the bottom so I have to put certain foods on certain shelves. This june ,the temps change from 85 night and vary 112 to low 120s during some days. I have to change the temp control manually sun up and sun down to keep the temp constant. This is just the start of summer. Any way to have it change my refers temps automatically?