Error Code 4
Freezer defrost sensor is faulty or its protective bimetal/fuse has opened
Critical
Stop using immediately - risk of damage or safety issue
Also displayed as: F and R LEDs blink (item 4)
What This Means
Loose or disconnected defrost sensor connector; Open or shorted defrost thermistor; Damaged wiring to defrost sensor; Bimetal or thermal fuse has opened (check separately)
What actually causes this:
The sensor that tells the board when the freezer is done defrosting has failed or the overheat protector has tripped
First Thing to Check
With the freezer at room temperature, unplug the defrost sensor connector and check that it is securely seated
Parts Involved
How to Fix
- 1
Check voltage at CN51 pin 5 (BLK) to pin 7 (WHT); should be 4.5V to 1.0V
- 2
Measure sensor resistance with connector unplugged; compare to DATA1
- 3
Check bimetal continuity (should be closed at room temperature): rated AC 125V 6A or 10A
- 4
Inspect thermal fuse: rated AC 250V 10A, opens at 228-230°C (109-110°C)
This Error Applies To
Samsung RF18A5101 Series Refrigerators (2021) (2021–present)
Related Error Codes
Fridge compartment defrost sensor is faulty or disconnected
Fridge temperature sensor is open, shorted, or disconnected
Ice maker temperature sensor in freezer is faulty or disconnected
Freezer defrost heater or its protection device has failed
Humidity sensor is faulty or disconnected
Fridge compartment defrost heater or protection device has failed
Freezer temperature sensor is open, shorted, or disconnected
External ambient temperature sensor is open, shorted, or disconnected