My side by side has a problem. I started to smell burning from in freezer. Then it stopped cooling. It sounds fine, but quit cooling. So I checked behind the back panel in the freezer and found that the defrost heater had blown up about 8 inches down on the right side. Is that my whole problem and I just need to get a new defrost heater? Or is there something else going on that caused that to happen?
A model number may help others help you.
I cannot say if the heater is your only problem.
What did the evaporator (freezer) coils look like when you looked at them.
If they were heavily iced/frosted over then it could be that the heater is the only problem.