Hi Jane, you did not state which make you have.
But from what you have said I am assuming it is a frost free unit.
The noise is probably from the fan motor touching a build up of ice.
The fan on these unit's nearly always stop on the door being opened.
Try defrosting the unit by turning off for a few days and retest. The fault may come back if you have an auto defrost fault.
Or is it possible the freezer door was left ajar for sometime ?.
randall refrigeration, September 2009