Error Code 21
Freezer compartment fan motor is not running
Critical
Stop using immediately - risk of damage or safety issue
Also displayed as: F and R LEDs blink (item 21)
What This Means
Failed BLDC fan motor; Ice blockage restricting fan blade; Wiring harness damage or loose connector; Failed MAIN PCB fan drive circuit
What actually causes this:
The fan that circulates cold air through the freezer has stopped working, usually due to ice buildup on the blade or a failed motor
First Thing to Check
Open the freezer and listen for the fan — if the freezer evaporator area is heavily iced up, run a manual defrost first
Parts Involved
How to Fix
- 1
Check voltage between CN51 pin 17 (S/BLU) and CN51 pin 19 (GRY); should be DC 7-12V when fan is commanded on
- 2
Enter manual operation mode (Test Mode FF) and verify fan operates
- 3
Check pulse feedback signal at CN51 pin 15 (PNK); should alternate ~2-3V when rotating
- 4
Check for ice on fan blade through cover
- 5
Check door switch is functioning and not causing fan to stop
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
Freezer defrost sensor is faulty or its protective bimetal/fuse has opened
Humidity sensor is faulty or disconnected
Fridge compartment defrost heater or protection device has failed
Freezer temperature sensor is open, shorted, or disconnected