Microwave displays F5 and will not start or stops unexpectedly.

Safety First: Unplug the microwave and be aware that the high-voltage capacitor can retain a dangerous charge. High-voltage troubleshooting should be left to professionals.

Basic checks (user-level):

• Power reset: Disconnect power for 10–15 minutes, then reconnect. If F5 returns immediately, internal control issues are likely.
• Visual inspection: If you remove the outer cabinet (only if comfortable), look for obvious burnt spots on the main control board or wiring harness. Do not touch or probe the high-voltage section.
• Do not bypass safety devices: Never bypass fuses, thermostats, or door switches to clear this error.

Recommended action: F5 typically indicates a control or high-voltage fault that requires professional diagnosis. A technician will test the Frigidaire main control board, high-voltage transformer, capacitor, and diode, and replace the defective component.