Microwave displays F3, may stop mid-cycle or refuse to start; sometimes accompanied by erratic heating times.

Safety First: Unplug the microwave and be aware that internal capacitors can hold a dangerous charge. Do not touch the high-voltage section.

• Allow to cool: If the unit has been used heavily, allow it to cool for 30–60 minutes, then try again. Overheating can temporarily trip thermal devices.
• Check airflow: Ensure the upper and rear vents are not blocked by cabinets, foil, or other objects. Poor ventilation can cause overheat errors.
• Inspect wiring (visual only): Remove the outer cover (only if you are comfortable and the unit is unplugged). Locate the cavity thermistor/thermostat near the oven cavity and visually inspect wiring for burns or disconnections.
• Test sensor (advanced): Using a multimeter, check the thermistor resistance against Amana’s service specs (commonly 10–100 kΩ depending on temperature). An open or shorted reading indicates a bad sensor.
• Replace faulty parts: Replace the cavity thermistor or thermostat if defective. If sensors and wiring are good, the main control board may be at fault and should be replaced by a professional.