Supco SZ3081180 Refrigerator Defrost Timer. This timer will activate for 21 minutes every 8 hours. This timer uses 120 volts. The defrost timer manages the automatic defrost system in the freezer. This defrost timer Equivalent To Sub-Zero 308110 and Frigidaire 5303917634.
Possible Repair Solution For:

Frost buildup, Fridge section is too warm, Fridge section is too cold, Freezer section is too warm, Freezer section is too cold, Fridge is running for too long, Freezer is not defrosting, Leaking water.
 
Please Note: This is intended as a guideline only, as other items can cause the same symptoms.