Refrigerator - Types of Defrost Systems

Almost all Refrigerators manufactured today have an automatic defrost system. The Refrigerator never requires any manual defrosting. Exceptions to this are typically small, compact Refrigerators. Listed below are the types of defrost systems and how they operate.

No-Frost / Automatic Defrost

Frost-free Refrigerators and Upright Freezers defrost automatically either on a time-based system (Defrost Timer) or usage-based system (Adaptive Defrost). For more information, please see our Refrigerator - Automatic Defrost System article.

• Defrost Timer: Measures a pre-determined amount of accumulated compressor running time; usually defrosts every 12 to15 hours, depending on the model.
• Adaptive Defrost: Please see our Refrigerator- Frost Guard / Adaptive Defrost article.

The defrost system activates a defrost heater in the evaporator section at the rear of the freezer compartment. This heater melts frost off of the evaporator coils and then turns off.

• During defrost there will be no running sounds, no fan noise and no compressor noise.
• Most models will defrost for approximately 25 to 45 minutes, usually once or twice a day.
• You may hear water dripping or sizzling as it hits the heater. This is normal and helps evaporate the water before it gets to the drip pan.
• When the defrost heater is on, it is normal to see a red, yellow or orange glow from the freezer.

Manual Defrost or Partial Automatic Defrost (Compact Refrigerator)

You must manually defrost by turning off the Refrigerator and letting it warm to room temperature. There is not a defrost heater in these models.

• Defrost whenever frost becomes 1/4 inch to 1/2 inch thick.
• Follow the instructions for defrosting in the care and cleaning section of the Owner's Manual.
• Fresh food compartment defrosting takes place automatically every time the refrigerator turns off. Melted frost water drains from the cooling coil into a trough on the rear wall of the cabinet and then down the corner to a drain tube at the bottom. Water flows into a pan behind the grille where it is evaporated.

Cycle Defrost

The Refrigerator fresh food section defrosts automatically by means of a thermostat affixed to the evaporator coils every time the appliance cycles off (usually every 20 to 30 minutes). However, the freezer compartment must be manually defrosted whenever frost becomes 1/4 inch to 1/2 inch thick.

• Fresh food compartment defrosting takes place automatically every time the refrigerator turns off. Melted frost water drains from the cooling coil into a trough on the rear wall of the cabinet and then down the corner to a drain tube at the bottom. Water flows into a pan behind the grille where it is evaporated.

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