The short answer
A MM machine that runs, lights and turns but does not heat has a specific short list, and two of the items on it are free to check. On a countertop machine the supply and the setting are both easy to prove, which is why they come before anything inside the case.
What you observe on these models
- The turntable turns and the light works but the food stays cold — The machine is running: the fault is in the heating path, not in the power path.
- It heats weakly rather than not at all — Weak heating points at the setting or the supply; no heating at all points at the door chain or the high-voltage side.
- A buzz or hum when heat is called for, with no result — Something is trying to run.
- It heats normally on some settings and not on others — That behaviour belongs to the control path rather than to the magnetron.
- NEAR MISS — nothing at all happens when start is pressed — That is a no-start fault and belongs on a different page.
Causes, most likely first on the MM family
- Low or shared supply voltage at the socket — First on this platform: a microwave draws heavily while it heats.
- Power level, cook time and the mass of what is in the cavity — Second: a machine set to a low power level cycles its output on and off, which feels like weak heating rather than none.
- A shared circuit sagging under another appliance — Third: a kettle or a toaster on the same circuit pulls the supply down at exactly the moment the microwave needs it, and the result is weak heating that comes and goes with the kitchen.
- The door interlock chain not fully making — Fourth: microwaves use more than one switch in the door, and on many designs the machine will light, turn and count down with one of them unmade while the magnetron is never enabled.
- The magnetron and the high-voltage side that feeds it — Last: this is the commonest hardware failure behind a machine that runs and does not heat, and it sits below the free checks only because it is the one that costs money to prove.
Check in this order, and why that order
- Heat a cup of water on full power for a short burst — It is the standard test because it removes the load, the setting and your expectations from the question in one go.
- Check the power level and the cycle actually selected — A low power level cycles the output and feels like weak heating rather than none.
- Reheat in a shallow dish rather than a deep one — It removes the load shape from the question.
- Let the machine stand unused for an hour and try again — A machine that heats after a rest was protecting itself rather than failing.
- Check the vents and the cavity fan path for grease — A machine that cannot cool itself cuts back before it fails.
Before you open anything
Safety
Unplug the appliance or switch off its breaker before removing any panel. A capacitor can hold a charge after the power is off. Treat that as the first step of every check below that involves a panel, a grille or a cover.
Models in the MM family — The numbers this page covers.
Reference| Model number | Family key |
|---|---|
| MM07V0W | avanti:microwave:mm |
When to call a technician
Settings, loads, sockets and the door latch are all owner checks on this machine. On these models the line falls at the outer case, and everything behind it. Call without working through anything at all for a socket or plug that heats under load, which is a fire risk rather than a nuisance.
Nearest pages of this class
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