H99
RCA
Inverter Overheat / Overcurrent Protection
Microwave intermittently shuts down with H99 error; may reset after cooling.
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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
Blocked ventilation causing inverter overheating, Failing cooling fan, Partially shorted magnetron, Defective inverter temperature sensor
How to Fix / Troubleshooting
Safety Warning: Do not attempt to service the inverter or magnetron yourself.
User checks:
- 1. Improve ventilation: Ensure the microwave has adequate clearance on all sides and that vents are not blocked by cabinets or objects.
- 2. Clean filters and vents: On OTR models, remove and clean grease filters. Vacuum dust from intake and exhaust vents.
- 3. Allow cooling: If H99 appears after long cooking sessions, let the unit cool for 30–60 minutes and test again.
If H99 recurs frequently even with good ventilation, the inverter, magnetron, or cooling system likely needs professional service.
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Repair Difficulty
Professional Required
5/5
Required Part
Cooling Fan Motor
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