Safety first: Disconnect power before touching or moving the appliance.

Step 1 – Isolate noise source: Run the Thermador microwave with a cup of water and listen carefully. Determine if the noise is from the top, side, rear, or bottom.
Step 2 – Check turntable: Remove the glass tray and roller ring. Clean and inspect them. Run a short cycle without the tray to see if the noise changes. If it stops, the turntable motor or tray components may be the cause.
Step 3 – Inspect fan (qualified persons): Remove the cover and check the cooling fan and, if equipped, convection fan. Remove debris and ensure blades are not rubbing against shrouds.
Step 4 – Check for loose parts: Tighten any loose screws on internal panels, magnetron mounting, and fan housings.
Step 5 – Magnetron diagnosis: If the noise is a deep, loud buzz synchronized with heating and persists after other checks, the magnetron may be failing and should be replaced by a technician.

Note: Do not operate the microwave with covers removed.

Microwave runs but makes loud buzzing, humming, or grinding noises during operation.

Possible Causes