SUF21SVR.....Door open alarm sounds when door has not been opened for an extended time. What can cause an alarm without alarm conditions being met. Door closes by itself when left at 45 degrees open. Seal is in excellent condition with no visible damage. Freezer is less than two months old. A thermometer has been placed inside the freezer and reads a constant zero degrees. Is the digital control in the door defective?

If your Whirlpool upright freezer is working fine but an intermittent alarm is sounding that is different from the high temperature alarm, it could indicate an issue with the door or the door switch. The alarm is designed to alert you if the door has been left open for an extended period or if the door switch is malfunctioning. Check the door seal to ensure it is tight and the door is closing properly. You can also try cleaning the door switch to see if that resolves the issue. If the problem persists, it may be necessary to contact a professional for further assistance.

Question edited for clarity, MAKER.
Question moved to Model Category.

Your fridge freezer has three fans.

The compressor evaporator fan cuts in and out as required to maintain temperature.

The fridge evaporator circulation fan runs to maintain an even temperature. It stops when to open the door and resumes when you close it and stops when the set temperature is reached as long as the compressor isn't running. If the compressor is running, the fan normally runs to prevent icing which happens slowly.

The freezer also has a fan, and that runs pretty much all the time unless target temperature is met and the compressor is not running. This fan runs when you open the door to stop the moist air from the room freezing on contact to the 0'F, -18'C evaporator fins. The fan keeps the air moving to deposit less frost.

It sounds like your is running normally except for the noise. Trace the noise and find it. The compressor fan has a Shark Paper fibre board cover and these often distort over time and touch the fan blades. That is the common cause. The less common cause is the internal fans pinging off built up ice that should have been removed during the defrost cycle.

If you are rearranging the things in the compartments this can cause the alarm to stay on: it depends if the door is open a long time.
My freezer has an alarm button to deactivate the alarm for this purpose.
Have you still got the user manual that came with your freezer?
If it is possible to deactivate the alarm, it will tell you how.

Warning light (red)
If the temperature warning light (4) lights up, it
indicates that the temperature within the freezer has
reached a level where the safe food storage is no
longer ensured. When the freezer is first switched on, the warning light will stay on until the temperature has dropped to
a safe level for the storage of frozen food.

Temperature acoustic alarm
This appliance incorporates an alarm which gives off
an audible signal whenever the warning light comes
on. This signal can be temporarily stopped by
depressing the push button for fast-freezing (6).
The fast-freezing push button can be released as
soon as the warning light is off.

Open door acoustic alarm
This appliance also incorporates an alarm which
sounds if the door is left open for more than 60
seconds. The signal will be stopped when the door is
closed again.

Dado

disconect power to alarm box. Wait ten mins and reconnect.

The freezer being closed up tight and so cold can create a negative pressure inside. This negative pressure will cause the door to be very hard to open and could pull the door closed too quickly. Most manufactures today use small air valves the open and release as the door is being opened and closed. They are most often found on the bottom of the door itself or sometimes in the cabinet behind the back wall.

The noise is perfectly normal, my wife says it is there to alarm her when I am eating too many ice cream bars.....

My wife solved it for me :-) You turn the alarm off with a switch at the bottom. The alarm turns off, but the light stays red for another 4 hours. After that the red light goes off too, and you can turn the switch back on without the alarm going off, if the freezer is back to operating temp.

You need to check the temp in the freezer to make sure it's down to around 10 degrees. The alarm will go off much above that.

if the alarm is sounding its probably trelling you the freezer is at too high a temperature. plug it in and leave it plugged in, it can take several hours to re freeze

that because the internal fan is hiting the ice or has bad bushings you can hear the noise just with the door close because when you open the door there is a switch the one turns off the internal fan so when you close the door it turn on the fan again if you wants to hear that with the door open just open the door and push the botton swich with your fingers and you'll hear the noise