Microwave intermittently stops heating and sometimes shows H99; may work again after cooling.

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.

Possible Causes

Overheating inverter module, Failing cooling fan, Poor ventilation around microwave, Degraded magnetron drawing excess current

Safety first: Unplug the microwave and allow it to cool.

User-level checks:

Ventilation: Ensure adequate clearance around the unit and that vents are not blocked.
Clean vents: Remove dust and grease from intake and exhaust vents.
After cooling and cleaning, test again with a short cycle. If H99 returns, internal components are likely overheating.

Next steps:

Have a technician inspect the cooling fan, inverter module, and magnetron for overheating and electrical faults.

Professional Required 5/5

Cooling Fan Motor

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