H99
Café Inverter Overload / Protection Trip

Microwave shows H99 and will not heat; may occur intermittently before becoming constant.

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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

Intermittent magnetron short, Overheating inverter, Loose high-voltage connections, Defective inverter board

How to Fix / Troubleshooting

Critical safety warning: Internal high-voltage repairs must be done only by trained technicians.

User-level steps:

  • Allow cooling: Unplug the Café microwave and let it sit for at least 30 minutes to cool internal components.
  • Check ventilation: Ensure that cabinet clearances meet Café installation requirements and that vents are not blocked.
  • Test again: Restore power and run a short cook cycle with water. If H99 returns, the inverter or magnetron is likely failing.
  • Service required: Schedule service with an authorized Café technician to test and replace the inverter board and/or magnetron.
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Repair Difficulty

Professional Required 5/5

Required Part

Inverter Board
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