My Microwave is making a loud humming noise, can anyone help?

Is it humming on its own without being started? If the humming is the same sound as when you are cooking something, there is something wrong with the control electronics that is not running off properly. Put a glass of water in it, close the door and verify that the water does not heat up. If it remains cold, at least the microwaves are not turning on by themselves. As long as the microwaves turn off properly you should be ok. The transformer in the power supply may be dying. Microwaves are cheap. If you are worried. buy a new one!

You have probably already diagnosed your problem as being the transformer. If you are electrically inclined you might be able to open the Microwave and just tighten the bolts that hold the transformer plates together. The noise is nothing more than something that is irritating to listen to and is a result of hitting a resonant frequency when AC is flowing through the coils.

If you can stand the noise, don't worry about it but if you have no experience in electronics stay out of the inner workings there are some very dangerous high voltage inside that can shock the crap out of you if not kill you.

@Mel

Just as a bit of information, transformers do not start to go out, they work and then a winding either opens or shorts at which point they quit working.

Kenmore Microwave Door

My microwave is doing the same thing, except when the door is closed it will heat things up even without setting the cook time or cook temp.

That's an appliance repair question. This is an Engineering forum.

be careful on what types of tupperware products your using, and no paper plates or paper towels, they are recycled and the metal grinders used for the process break down and create havoc for the microwaves

the bussing in the microwave is coming from the high voltage capacitor does this mean it"s bad