Microwaves

Microwave seems to keep running or hums after opening the door

A microwave should stop generating microwave energy the instant the door opens; any hum or apparent activity after opening is a serious safety concern and should be checked immediately.

Difficulty
Professional only
Time
Immediate
Pro cost
$100–$220

Symptoms

  • Humming or buzzing continues briefly after the door is opened
  • Turntable may keep moving for a moment after opening
  • Display may still show a countdown continuing
  • This happens consistently, not just once

Likely causes

  • CommonDoor switch failing to fully interrupt the circuitThe interlock switches are supposed to cut power to the magnetron the instant the door opens; a fault here is a real safety issue.
  • PossibleTurntable motor simply coasting brieflyA turntable continuing to spin for a second from momentum after stopping is not itself dangerous, unlike a continuing hum.
  • Less commonControl board faultRarely, the board itself could misbehave in how it manages the interlock signal.

What to do

  1. If you hear a hum or buzzing sound continue after opening the door, do not put your hands or face near the opening.
  2. Unplug the microwave immediately and do not use it again until it's inspected.
  3. Distinguish this from the turntable simply coasting for a second from momentum, which by itself is not a safety issue if there's no continued hum.
  4. Do not attempt to test this repeatedly to confirm; treat a single instance of a continuing hum as reason enough to stop use.
  5. Do not open the case or attempt to inspect the door switches yourself.
  6. Have a technician inspect and repair the door interlock system before the microwave is used again.

Tools and parts

Microwave door interlock switchSearch: “microwave door interlock switch replacement”

When to call a pro

Call an appliance technician immediately to inspect and repair the door interlock switches; do not attempt to use or open the microwave in the meantime.

Safety

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.