Symptoms
• Freezer temperature rises above the normal freezing range
• Control panel displays E21 error code
• Compressor cycles on and off irregularly
• Freezer beeps or sounds an alarm
• Frozen food begins to thaw or shows signs of partial thawing
• Interior light may flicker or behave erratically
• Refrigerator section (if combo unit) may also experience temperature fluctuations
• Freezer temperature fluctuates between too cold and too warm
• Excessive frost or ice buildup on interior walls and shelves
• Error code E21 displayed on the digital control panel
• Freezer not maintaining set temperature despite adjustment attempts
• Compressor running continuously or cycling erratically
• Food items freezing inconsistently or thawing prematurely
• Audible alarm or warning tone accompanying the error display
• Interior light functioning normally while temperature control fails
Possible Causes
• Faulty temperature sensor (thermistor) located in the freezer compartment
• Loose or corroded wire connections between the sensor and control board
• Damaged sensor wiring from frost buildup or physical damage
• Control board malfunction preventing proper sensor signal interpretation
• Power supply voltage fluctuations on the 120V/60Hz household circuit
• Ice accumulation around the sensor probe blocking accurate temperature detection
• Failed connector or harness between sensor components
• Defrost thermostat malfunction or sensor failure
• Loose or corroded electrical connections to the temperature sensor
• Damaged or pinched thermostat wiring harness
• Control board failure preventing proper sensor signal interpretation
• 120V power supply voltage fluctuations affecting sensor circuit
• Failed thermal cutout switch in the defrost heater circuit
• Moisture infiltration in the sensor connector causing electrical shorts
• Calibration drift in the temperature sensing component
Safety Checks You Can Do
• Verify the freezer is plugged into a functioning 120V outlet and check your home's circuit breaker for any tripped breakers
• Unplug the freezer for 5 minutes, then plug it back in to reset the control board and clear the error code
• Inspect the freezer door seal for gaps, cracks, or poor closure that could allow warm air to enter and confuse the sensor
• Clean the condenser coils located on the back or bottom of the freezer to ensure proper heat dissipation
• Check that the freezer is not overpacked with items blocking internal airflow and vents
• Verify the room temperature where the freezer is installed is between 50°F and 110°F (the recommended operating range for USA models)
• Look for any visible ice buildup around the temperature sensor area and use a soft cloth to gently remove it
• Ensure the freezer is installed with proper clearance from walls (typically 2-4 inches recommended) for adequate ventilation
• Test the outlet with another appliance to confirm the electrical outlet is providing stable power
• Verify your home circuit breaker has not tripped by checking the electrical panel and resetting if necessary
• Unplug the freezer for 5 minutes, then plug it back in to perform a soft reset of the control board
• Inspect the freezer door seal for gaps, cracks, or debris that may cause temperature sensor confusion
• Ensure the freezer is not positioned in a garage or room where ambient temperature falls below 50°F or exceeds 110°F
• Check that condenser coils on the back or underneath the freezer are free of dust and pet hair buildup
• Verify the freezer interior is not overpacked with food items blocking air vents and sensor access
• Confirm the freezer is level and not tilted, which can affect internal drainage and cooling distribution
• Look for visible signs of water pooling or frost formation that might indicate a defrost cycle malfunction
Safety First
Always disconnect the appliance from power before performing any checks. If you are unsure about any step, please contact a qualified technician.