Microwave making a loud humming noise while running (all brands)
✅ Safe to check yourself
This is a common, low-risk check most people can do safely. Always unplug the appliance (or isolate power) before touching internal parts.
Quick TipTake a photo of the appliance's model/serial number sticker now — you'll want it if this does end up needing a part or an engineer.
Microwaves are naturally not silent — the transformer, fan, and turntable motor all produce some background noise during normal operation, so the real question is usually whether the noise is new, louder, or different in character than usual, not whether there’s noise at all.
What’s normal
- A steady hum from the transformer throughout cooking is completely standard.
- Fan noise, particularly noticeable just after cooking finishes as the appliance cools down, is also normal.
What to check if it seems different
- Check whether the noise correlates with the turntable — remove it and run briefly empty (never run a microwave completely empty for more than a few seconds, and only to isolate a noise source) to see if a grinding or rattling noise specifically tracks the turntable’s rotation, pointing to the roller ring or drive coupling rather than the microwave’s core components.
- Check the appliance is sitting level and stable, not vibrating against a cupboard or wall, which can make an otherwise normal internal hum sound much louder than it actually is.
- Check the vents aren’t obstructed, which can make the fan work harder and louder than normal.
When to call an engineer
If the noise is genuinely new, distinctly different (a buzz or rattle rather than a steady hum), and isn’t traced to the turntable or vent obstruction, this is worth a professional check given the internal high-voltage components involved — not a casing-open DIY job.