Microwave makes loud buzzing, humming, or grinding noises when heating.

Safety: Unplug the microwave before removing the cabinet. Avoid touching high-voltage components.

• Isolate noise source: Run the microwave briefly with a cup of water and listen carefully to locate the area of the noise (top, side, bottom). Then unplug and inspect that area.
• Check fan and turntable: Inspect the cooling fan and turntable motor for loose blades or mounts. Tighten screws and remove any foreign objects.
• High-voltage hum: A deep, loud hum often indicates a failing magnetron or transformer. Look for burn marks or discoloration.
• Replace noisy parts: Replace the cooling fan motor, turntable motor, magnetron, or transformer as indicated. High-voltage component replacement should be done by a professional.