H99
Maytag
Inverter Overheating or Protection Trip
Microwave displays H99 and will not start or stops immediately.
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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
Overheated inverter, Blocked internal cooling airflow, Failing cooling fan, Defective inverter board
How to Fix / Troubleshooting
Safety first: Disconnect power before inspecting vents or internal components.
Ventilation and cooling:
- Ensure that all external vents are clear and that the microwave has proper clearance per the installation manual.
- Clean grease filters and any accessible vent screens.
Fan check:
- Listen for the internal cooling fan when the microwave runs. If it is not running or is very noisy, the fan may be failing.
Professional service:
- H99 often indicates an inverter or cooling issue that requires internal testing.
- A technician may need to replace the inverter board and/or internal cooling fan motor.
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Repair Difficulty
Professional Required
5/5
Required Part
Inverter Board
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