Microwave displays F8 and may not heat or may shut down during cooking.

Safety: Unplug the microwave. Internal components can carry high voltage.

• Check vents: Ensure front, side, and top vents are not blocked by cabinets, foil, or debris. Clear any obstructions.
• Listen for fan operation: When the unit is running (before it errors), you should hear the internal cooling fan. If it is silent or very noisy, suspect the fan.
• Inspect fan: Remove the outer cover (for countertop units) or top grille and mounting screws (for over-the-range models) to access the cooling fan. Check for food debris or insulation blocking the blades.
• Spin test: With power off, spin the fan blades by hand. If stiff or seized, replace the fan motor assembly.
• Replace fan or board: If the fan motor tests open with a multimeter or does not receive power when commanded on, replace the fan motor. If the motor is good but never gets power, the control board fan relay may be faulty and the board should be replaced.

Do not operate the microwave with a non-functioning cooling fan; this can damage the magnetron and other components.