Error code
F-DEF ERROR
Meaning
The freezer defrost heater isn't working
Moderate
What to do
Why this happens
Possible causes include an open or slipped-out connector, wire cuts or shorts, a defective defrost thermistor, an open or faulty bimetal, a blown thermal fuse, or an open defrost heater element.
How to fix it
This one needs a professional technician
SourceSamsung service manual