No-bake cheesecake - freeze or chill overnight?
Your refrigerator should be set at a temperature below 4 Celsius. If it isn't, then you are exposing yourself to danger from eating the other things stored there. 

At this temperature, the cheesecake will keep perfectly without the icing deforming. Indeed, it will probably even keep well if the fridge temeprature is slightly high. 

Under no circumstances should you increase the temperature of your freezer. The cake risks texture change if it freezes. A freezer should always be kept below freezing, or else the other food stored in there will take large hits to both quality and safety.