Unit emits a high-pitched whining or electrical buzzing noise when heating.

Safety first: Unplug and cool the unit before opening.

• Identify source: Run a brief test and listen carefully to locate the noise (control board area vs. fan area).
• Inspect control board: Look for loose or vibrating components such as coils or transformers on the main control board. Gently press with an insulated tool (unit unplugged) to see if movement is possible.
• Secure components: Where safe and appropriate, apply high-temperature-safe silicone or adhesive to secure vibrating coils.
• Check fan motor: If the noise tracks with fan speed, inspect and replace the convection fan motor if necessary.