Error code reference

Panasonic Air Conditioner Error Code H99

Indoor operating unit freeze protection (cooling)

Indoor operating unit freeze protection (cooling) — indoor freeze prevention control activates 5 times in 60 minutes during cooling or soft dry.

First step from the service manual

Check for air short circuit at the indoor unit.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
  • Verified part numbers when replacement is required
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