Clean or change the gasket.
Frigidaire freezer door ajar sensor.
The door ajar indicator will remain lit until the door is closed.
These alarms tell you if the door stays open the temperature inside the appliance rises to unsafe levels or the unit has experienced a power failure.
I did locate a link that will discuss your situation in greater detail.
After hitting the reset switch the alarm stops but resumes in about 5 10 minutes after the third reset the alarm no longer goes off.
Frigidaire freezer lffh21f7hwg changed out door gasket due to door ajar alarm would not clear and gasket was damaged due to wear.
Whenever the door or lid is opened the warm air that enters can cause the temperature in the freezer to rise triggering the freezer to run in order to lower it again.
I can understand your concern over your freezer thinking the door is ajar.
Frigidaire refrigerators and freezers generally come with three built in alarms.
There is no denying that these audible tones can create an annoyance but they all exist to ensure that the food you eat stays safely cooled.
I might even suspect the switch itself.
Do you know the model of your frigidaire freezer.
How old is it.
If the light stays on when the switch is manually pressed it would indicate the control board might have failed.
The alarm stopped but then it started up again.
Over 10 years old not sure of the model.
I pressed the reset button and unplugged it for 30 seconds.
Its set at 0degrees and the door is closed securely.
Leaks in the gasket seal can let warm air in causing your freezer to run more in order to maintain the desired temperature.
My frigidaire upright freezer door ajar alarm is beeping.
Then check the freezer.