Error Code 21E
Freezer defrost heater or safety cutoff device failed
Moderate
Address soon - your appliance may not work properly
Also displayed as: 21E
What This Means
Defrost heater housing connector separated at CN70; Defrost heater wire open-circuited or short-circuited; Thermal fuse blown (230°F/110°C cutoff); Bimetal thermostat stuck open; Failed defrost heater
What actually causes this:
Most commonly the thermal fuse has blown (one-time device, not self-resetting) due to a previous defrost cycle where the bimetal failed to cut off the heater in time, causing overheating.
First Thing to Check
With power OFF, measure resistance between CN70 pin 7 and pin 1 — an infinite reading means the heater circuit is open; check the thermal fuse first.
Parts Involved
How to Fix
- 1
Disconnect Main PCB CN70 connector from PCB
- 2
Measure resistance between CN70 pin 7 and pin 1
- 3
0 Ohm indicates heater short-circuit — inspect heater and wiring
- 4
Infinite (∞) Ohm indicates open circuit — check heater, thermal fuse (230°F/110°C), and bimetal (Off 140°F/On 104°F)
- 5
Normal heater resistance is per wiring diagram values
This Error Applies To
Samsung RF34H9950S Series Refrigerators (2018) (2018–present)
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