Hi,Welcome to Just Answer, My name isXXXXX will be helping you with your appliance issue today.
Can you get me the full model number? Is this a dryer?
Well yes it's okay but you will need to replace that timer, most likely the motor on the timer is bad so this means it'll keep running but won't defrost because the motor is not turning the timer to get to the defrost mode in so the refrigerator will freeze up and start cooling again only this time the freezer will probably stay cold but the refrigerator will not because of Frost buildup, you can order this timer at the following link,
http://www.repairclinic.com/Shop-For-Parts?s=t-%20241621501-%3d%3d there will be a couple screws to take out to drop that control panel down so you can replace it, it's pretty simple to replace, hope this helps, thanks and very best wishes, Bryan