- “The magnetron circuit: magnetron, diode, capacitor or transformer”
- “Nothing else in the machine has to be wrong for this to happen”
- “On a built-in or over-the-range unit repair is usually right; on a countertop it may not be”
Symptom
LG microwave not heating
One of the most specific symptoms in this trade. Everything else about the machine works — the turntable turns, the fan runs, the light comes on and the timer counts down — and the food stays cold. That combination points at one circuit, and it is worth an honest conversation about what repairing it costs.
- From $95 diagnostic, credited to the repair
- 59 cities and neighborhoods covered
- OEM parts available on order
- In writing the price, before anything is opened
Four ordinary causes
What this usually turns out to be
Cheapest and commonest first, which is also the order we check them in. They sit hundreds of dollars apart, and only the unit settles which one is yours.
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The magnetron
The part that makes the microwaves. It fails, and there is no partial version of it.
Microwave repair from $185 -
The high voltage diode or capacitor
Cheaper than the magnetron and produce exactly the same symptom.
Microwave repair from $185 -
The transformer
Less common, and it usually announces itself with a smell.
Microwave repair from $185 -
A door interlock in a partial state
Some interlock arrangements will let the machine run and inhibit the magnetron.
Microwave repair from $185
In five minutes
Before you call anybody
None of it needs tools, and all of it makes the visit shorter.
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01
Run the one-cup test
A minute, a mug and cold water. It settles the question.
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02
Listen for the hum
A working magnetron circuit is audible under the fan. Silence where a hum should be is informative.
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03
Check nothing is on the door seal
A door not closing fully is a different and much cheaper problem.
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04
Do not open the case
The capacitor in a microwave holds a lethal charge long after it is unplugged. This is the one appliance we ask people not to open.
How it shows up
What people describe when they call
A shortcut
Narrow it down before anybody arrives
A description of the behaviour leaves a few possible causes. A code names the subsystem before anybody opens anything, which is why it is worth photographing before it clears.
If there is no code at all
On a drawer, a microwave or a coffee system, the data plate is on the frame of the opening — open it fully and look along the sides. All models
In more detail
About LG microwave not heating
The one-cup test
Put a plain glass or mug with about a cup of cold water in the middle of the cavity and run the machine on full for one minute. Water that is noticeably warm afterwards means the microwave is producing power and the complaint is about time or quantity rather than the machine. Water that is exactly as cold as it went in confirms the diagnosis, and it takes a minute.
What it usually means, by the kind of LG appliance
LG sells one appliance in several forms — five shapes of washer, three kinds of dryer, four fuels of range — and the same behavior points at different things on each of them. A built-in side-by-side and an integrated column are not the same service situation, and a dual-fuel range and an induction range fail in different halves.
- Over the range — Worth repairing nearly always, because the installation, the trim and the ventilation are part of what you paid for.
- Countertop — The honest arithmetic often favors replacement, and we will say so.
- Combination wall oven — Definitely worth repairing — the microwave is half of a built-in cabinet and cannot be swapped for a countertop machine.
Why nothing else being wrong is the diagnosis
A microwave has two nearly independent halves: the machinery you can see — turntable, light, fan, controls — and the high-voltage circuit that actually cooks. The first runs on ordinary mains and the second on several thousand volts produced by a transformer, a capacitor, a diode and the magnetron. So a machine where everything visible works perfectly and nothing heats is not a mystery. It is the second half, and only the second half.
The honest arithmetic
On a countertop machine, the parts and the labor together often approach the price of a new one, and we will tell you that rather than sell you a repair that does not make sense. On an over-the-range machine or the microwave half of a combination wall oven it is different: you are not just buying a microwave, you are buying the cabinet, the trim, the ventilation and the fit — and repairing is nearly always the right answer.
This article is based on:
- Official manufacturer documentation
- Internal repair procedures
- Technician repair history
- Company quality standards
Before you book
Questions about LG microwave not heating
Is it dangerous to keep using it?
A machine that runs and does not heat is not leaking anything — it is producing nothing. The danger in a microwave is the reverse case: a door that does not seal or an interlock that has failed. What is dangerous is opening the case, because the capacitor stores a charge that can be lethal weeks after it was unplugged.
It heats slowly rather than not at all.
That is usually not the magnetron, which tends to work or not. Slow heating is more often low supply voltage, an overloaded circuit, or simply a machine of a lower wattage than the last one. Worth measuring before anything is replaced.
Where we do it
Across Miami-Dade, Broward, and Palm Beach
Same terms everywhere we go: an on-site diagnostic first, the price agreed in writing, and the exact figure confirmed once we have seen the unit.
Neighborhoods people ask for by name