Safety First: Disconnect power. Internal components can be hazardous.

Steps:

Check vents: Ensure the upper and rear vents are not blocked by cabinets, filters, or debris. Clean grease filters on over-the-range models.
Listen for fan: When starting a cook cycle (before F8 appears), listen for the internal cooling fan. If it does not run, suspect the fan motor or control.
Access fan (advanced): Remove the outer cabinet to locate the internal cooling fan (usually near the magnetron). Check for obstructions and spin the fan blade by hand (with power off) to ensure it moves freely.
Check wiring: Inspect the fan harness and connectors for damage or loose connections.
Replace fan: If the fan is seized or open-circuit, replace the Frigidaire internal cooling fan motor. If the fan tests good but never receives power, the main control board or fan relay may be defective.

Note: Because the fan is near high-voltage components, many users should have a technician perform this repair.

Microwave displays F8 and will not heat or start certain sensor functions.

Possible Causes