The bleeping sound will be an attention getter to alert you to a malfunction or error condition.
The user manual will give you guidance - it will very probably be temperature related and perhaps something as basic as a door not closing properly - but could be something more serious.
You can stop the beeping by resolving the problem or by disconnecting the power.
You do not say the make & model but it hardly matters - well not to me it doesn't.
Good luck...
Peccavi
July 2013
howtomendit.com for free repair help, information and advice.
