H99
Amana
Inverter Protection / Overcurrent Fault
Microwave displays H99 and will not start or stops immediately after pressing Start.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Shorted magnetron drawing excessive current, Inverter board overcurrent protection trip, Shorted high-voltage wiring, Defective inverter board current sensor
How to Fix / Troubleshooting
Safety First: Unplug the microwave. High-voltage components are hazardous.
- Allow cooling: Let the unit sit unplugged for 30 minutes to allow any thermal protection to reset.
- Check for obvious damage: If you are qualified to remove the cover, inspect the inverter and magnetron for burn marks or melted connectors.
- Do not bypass protection: Never attempt to bypass fuses or safety devices to clear H99.
- Professional diagnosis: H99 typically indicates a serious high-voltage fault. A technician will test the magnetron and inverter and replace the defective part.
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Repair Difficulty
Professional Required
5/5
Required Part
Inverter Board
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