My freezer keeps heating up. Not just not working, but heating. The inside ceiling of the freezer becomes hot to the touch. When I unplug the fridge and plug it back in it starts to cool again. I bought the fridge with the house, do not have a manual nor do I know how old the fridge is. Have always had a manual defrost fridge before this. Can you tell me the age of the fridge and if I just need to defrost it? Thanks