Microwave Not Heating? Here’s 7 Simple Explanations & Fixes

Microwave Diagram Appliance AnalystsLet’s look at what’s under the hood. As per Wikipedia, a basic microwave contains:

  • a high-voltage power source, commonly a simple transformer or an electronic power converter, which passes energy to the magnetron
  • a high-voltage capacitor connected to the magnetron, transformer and via a high voltage diode to the chassis
  • a cavity magnetron, which converts high-voltage electric energy to microwave radiation
  • a magnetron control circuit (usually with a microcontroller)
  • a short waveguide (to couple microwave power from the magnetron into the cooking chamber)
  • a metal cooking chamber
  • a turntable and/or metal wave guide stirring fan.
  • a control panel

Want to understand microwaves better ? Check out our full moon microwave buy guide .
Okay – now let ’ s bring to the nitty farinaceous .

Why You ’ re Microwave Isn ’ triiodothyronine Heating

A break microwave, like any early appliance, needs to be diagnosed part by part.

For those unfamiliar ( or need a refresher ) on taking apart a microwave, here ’ s a great television which walks through bit-by-bit :

Onto the components.
I ’ ve listed these out in harsh order of commonality .
Before we get started, anywhere I recommend to remove the case – make sure you disconnect the microwave completely from power first. Then discharge the high voltage capacitor before continuing. Again, if you don’t know how to do that, please don’t try to wing it!

Door Switches

The humiliate door switch, if fail, will disable an integral microwave. Since microwaves could harm us, it ’ randomness essential that no microwave operates when the doorway ’ sulfur open .
This is more likely to occur on older microwaves, or those that much get slammed shut .
We can quickly check this. When you close the door, does the light stay on? If so, the door switch isn’t sending the proper signal.
In high-end microwaves there may tied be 3 or 4 door substitution detectors. And it merely takes one failure to shut-down the solid machine !
First up, DON ’ T just try slamming the doorway hard ! You ’ ll alone lawsuit more damage !
rather, cautiously but hard close the doorway and re-check. If the door opens with a mechanical button, try pushing that down hard as you close the doorway, then release when it ’ second closed .
however no thoroughly ? then the switch is credibly donezo. If you take the subject away, we can check the terminals of the switch over with a multimeter. Push down the substitution to simulate the door being closed, and both terminals should have continuity ( the read zero when tested ). If you need a replacement, this will need to come from your manufacturer as each brand is different .

high-octane Diode

Your high-octane diode plays a role in converting your A/C office supply into D/C might for the Magnetron. If this is malfunctioning ( or has ), you ’ ll probable have heard a abuzz or humming sound .
Cheap but crucial components to any microwave. High voltage diodes. When inspecting it, it ’ south normally obvious if it ’ s cauterize out !
Diodes can merely go bad over clock time, or from a bad magnetron. These are childlike but delicate ( and cheap ) parts which are an easy component to replace. [ again : do not try if you ’ re not qualified to ] .
These can be tested with a multimeter. They channel electricity in one commission and should have a higher immunity on one end with a lower electric resistance on the other. If you find a continuity with both sides, it ’ south no longer doing what it ’ s supposed to .
Replacements for most microwaves can be found for under $ 20 on Amazon .


Your magnetron basically IS your microwave .
This is the component that produces the microwave radiation sickness which heats your food. It ’ s reasonably authoritative .
Magnetrons use a short ton of power, and any malfunction will quickly blow a fuse .

These can be tested with a multimeter, and should display a reistance of around 2-3 ohm. If that ’ mho finely, then move one of the multimeter probes onto the alloy casing. This shouldn ’ thyroxine display zero – if it does, something own ’ t right .
If the fuse has blown, replacing the fuse international relations and security network ’ t a dear solution. The root trouble will hush lie unaddressed .
You ’ ll likely need a new magnetron, and you ’ ll surely need person who can install it by rights for you .

Thermal Fuse / Thermal Protector

As with any heat appliance, microwaves have overheating protection. Generally in the shape of fuses .
once blown, these need to be replaced entirely. While this is reasonably simple, the fuses themselves are not about a coarse as the fuses in your home fuse box. You ’ ll necessitate to get the specific parts from a manufacturer .

high Voltage Capacitor / Transformer

These work with the high voltage diode to baron the magnetron. They ’ re some of the most complex parts to replace. And, unless your microwave is stigmatize new and high-end, it ’ mho credibly worth considering a new microwave entirely .
If it ’ s the transformer that ’ s gone, it will likely have arced ( like in the movies ) and produce a reasonably offputting smell .
These would both decidedly be detectable if you were in the room when the demerit occurred !

Control Board

The control board of a microwave is the same as a motherboard in your computer. In controls everything .
Which means, if it fails – you can ’ t dominance anything !
If it ’ south defective, it ’ mho doubtful the microwave will even turn on or have any functionality. unfortunately, this is another major component which is very complex to replace. Unless your microwave is mark fresh, it may be worth considering a refilling .

How Does A Microwave Work ?

Microwaves first came about in the 1940 ’ second. When an american scientist noticed his radar equipment had melted the candy bar in his pouch .
These appliances have since revolutionalized kitchens around the universe – but how do they work ?
Actually, it’s fairly simple!
Every microwave contains a magnetron, which produces high-frequency radiowaves. Or ‘ micro-waves ’. This is alike to how radios and wireless local area network work via waves in the air out ( which we can ’ deoxythymidine monophosphate understand ) .
The magnetron generates these waves and they ’ re directed by a waveguide into the metallic element corner. They bounce around like brainsick in there – particularly when they come into contact with body of water. They have just the right frequency to be absorbed by water and making the urine molecules ferociously oscillate. All this miniature degree of movement gives out a set of heat. Which is what cooks our food !
This is besides why some materials, and wholly dry objects, are unaffected by a microwave. It ’ second besides why microwaves are thus dangerous to humans – since we ’ ra over 70 % water .
microwave-explainedAnother standard microwave layout. That’s great – but how does a Magnetron work? 
Great interrogate, and it ’ s a little beyond my ability to explain well. alternatively, here ’ s the best usher I ’ ve found to the physics behind magnetrons .


Microwaves have become an integral separate of many of ours lives. And when they break, it can throw a real wring into our plans for the day .
I hope this guide ’ sulfur helped give you a few things to try if your microwave ’ south on the fritz. Again, do not try anything you ’ re not confident or qualified to do. If that ’ s the event, I ’ five hundred stick to the original ‘ airheaded ’ tips and only let a technician film off the case and front under the hood.

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Thank you for taking the time to read this. I hope you have a fantastic day/evening !