Refrigerator freezer side not freezing

Refrigerator & Freezer Repair
1

Please make sure to click on General above and select the correct appliance type first.

Brand:Frigidaire
Model Number:LGUS2642LEO
Main Symptom:freezer side temperature fluctuations
What happens & when:temp set on zero. Stays on zero a while then gets as high as 15, little ice build up in back.

Error Code (if any):
Parts or tests already tried:
Photos / video link:

2

Little ice buildup on the back wall plus temp swings usually points to a defrost issue or weak evaporator fan.Could be the defrost heater thermostat or control board not clearing frost properly which slowly blocks airflow and warms the freezer up.