Microwave makes loud buzzing or humming noise when running, with reduced or no heating.

Safety warning: Unplug the microwave immediately if the noise is accompanied by burning smell or smoke.

• Step 1 – Identify noise source: Run the microwave briefly with a cup of water and listen carefully (door closed). If the noise is metallic rattling, it may be a loose panel; if a deep loud buzz, suspect high-voltage components.
• Step 2 – Check external items: Ensure the microwave is not touching cabinets or objects that can resonate. Adjust feet to stabilize.
• Step 3 – Internal inspection: With power disconnected, check for loose screws on the transformer and chassis panels. Tighten as needed.
• Step 4 – Professional repair: Persistent loud buzzing with poor heating usually indicates a failing magnetron or transformer and must be handled by a technician.