OK, I'm going to look over your model and service manual. I do need you to tell me if the noise is
continuous or a one time pop? Two years old is almost new so let me try to help you. Click Here=>
ATB1836AR for your service manual. Your defrost heater has a glass tube surrounding it and can find a link or photo at the next two links
just click on repair guy and enter part number is part number=>
63001387 The defrost thermostat is part=>
63001388 and the defrost timer is part number=>
63001353 I would like you to open freezer and examine the rear wall for a layer of frost. If yes the we most likely have a defrost problem caused by one of these three parts. If yes also unplug and lets examine the defrost heater and defrost thermostat. Some people have the parts and some don't.
If you should need me you may find me here at Fixya or here=> Appliance 911. If you still need assistance, contact me here at
Fixya or through my site
HERE or here Sea Breeze Appliance Parts feel free to ask any time, Sea Breeze