Fan: Microwaves have a built-in fan that helps circulate air to keep the appliance cool during use. If you hear a humming or whirring noise, it may just be the fan running.
Turntable: If your microwave has a turntable, it may make noise as it rotates during cooking.
Magnetron: The magnetron is the component in a microwave that generates heat. If you hear a buzzing or humming sound while the microwave is in use, it could be an issue with the magnetron.
Defective Parts: In some cases, strange noises may indicate a problem with one of the internal components of your microwave. For example, if there is a loose part rattling around inside the appliance, you may hear banging or clanging sounds.