Microwave doesn't heat anything

If you're talking about a microwave oven:
[1] plug the mains cord in to the wall socket
[2] switch the socket on
[3] put food to cook on glass turntable, never use empty oven.
[4] close oven door fully until it clicks
[5] set the power
[6] press 'start' or turn the timer-dial,depending on your model.
It will start to cook immediately.
The humming sound is the energy heating the food in timed bursts of power.
If nothing happens or it won't cook, post clear description of fault with problem, make, model.
Hope this helps,
Clive.

could be anything from a bad mag or door switch or even a bad connection at the mag. Need more details. Any odd sounds??? A louder more pronounced humming sound??? Bad smells?? etc

you either have a bad magnatron, that is trying to heat but won't or you could have a capacitor or diode (rectifier) that is bad. if you order a magnatron replace capacitor and diode (rectifier)

Your magnetron that actually does the cooking is making that humming sound. That part needs to be replaced before it starts blowing your fuse inside the microwave. That part is the one located on top behind the control panel of your microwave and is about the size of a persons hand (sometimes smaller sometimes bigger). With everthing unplugged you can take the cover off and see it. It has some cooling fins on it and is held in place with only three to four screws. There are three to four wires that come out of it and go to only a couple of places one of them being a large capacitor that is about three to four inches long with terminals at its top. Find a magnetron at a local tv repair shop (reputable), a local electronic supply house (they can order you one) or on the internet. They cost from $25 to $60 depending on size of microwave. If you can do it yourself you can save about $40 to $50. Let me know how it goes. Good luck.

We are having the same problem with our XL1400. I suspect it has something to do with the turn table but don't know for sure. We would be willing to disconnect the turn table...anything to stop the noise but don't know how.

Popcorn is heated by a metallic insert in the bag. This causes some additional power consumption by the magnetron. It is no cause for alarm.

In order to try to set your mind at ease I will have to explain the Basics on how a Microwave Oven Functions.
When a Microwave Oven is set to COOK ...START. It cooks at 100%. There is no lowering of the heat as with a Range ( Cook Top) Control. So in order to do the other things such as DEFROST, WARM, or anything other than 100% COOK. A COOK ON- COOK OFF system was utilized. To DEFROST, the Microve COOKS at 100% for 30% of the TIME, then IDLES for 70% of the TIME. COOK ON 30% of the TIME, COOK OFF 70% of the TIME = DEFROST This is why you can hear the CYCLE. More power is required during the ON CYCLE, thus the lower vibration. The Vibration occurs when the High Voltage Transformer is turned ON ( COOK ON).
The VIBRATION seems to have got louder with age. This is somewhat normal as there is a vibration from the High Voltage Transformer present every time the Microwave is used. screws and other metal parts seem to get loose with this vibration. There is no solution, unless you can tighten EVERY screw, nut, and bolt in the unit.
Sorry!

Generally, the most common causes of a failure to heat are:

- bad door switches or door switch mounts
- loose connection at the magnetron
- problem or loose conneciton on the control unit circuit board
- bad magnetron or other high voltage part

If you or a friend decide to look into it, we have critical safety information, info on door switch diagnosis and replacement, and disassembly information at our site, linked here on Fixya: http://tinyurl.com/yzjozk

I was going to suggest the low voltage transformer, but when you said it sounded like it was coming from the left side, that seemed odd. I have a stock transformer here I keep for test that is loud, but it works. Odd, eh?

In my professional opinion, it sounds like you have a shorted relay or other defective component on your control circuit board, which is actually made by Samsung. We regularly repair these control panel assemblies nationwide for $32.50, so the problem can certainly be fixed economically. Looking at typical microwave wiring shows it has to be the cooking relay or a device that drives that relay. Since it stops when you open the door, we can say the door switches are certainly doing their job.