If your microwave is making noises even when it's not in use or when there's nothing inside being cooked or heated, there could be a few potential reasons for this:
Fan Operation: Many microwaves have built-in cooling fans that help regulate the temperature of the internal components. These fans may continue to operate even after you've finished cooking to cool down the microwave. The noise you hear could be the sound of the fan running. This is typically normal and nothing to be concerned about.
Internal Components: Microwaves contain various internal components such as transformers, motors, and relays. These components can sometimes produce humming or buzzing sounds, especially if they are older or if they have become worn over time. While some level of noise is normal, excessive or unusual noises could indicate an issue that may require professional inspection or repair.
Mechanical Issues: The turntable or rotating plate inside the microwave may occasionally make noise if it's misaligned or experiencing mechanical issues. This can happen even when the microwave is not in use. Make sure that the turntable is properly positioned and that there are no obstructions or debris causing it to make unusual sounds.
Electrical Issues: In rare cases, electrical problems within the microwave can cause strange noises. It's possible that there may be a loose connection or a faulty component that is causing the noise. Electrical issues should be addressed by a qualified technician to ensure safety and proper functioning of the appliance.
If the noise is persistent, excessively loud, or accompanied by other unusual behaviors, it's recommended to contact the manufacturer's customer support or a professional appliance repair service to diagnose and resolve the issue. They will have the expertise to assess and address any problems with your microwave.