P3
Fraser-Johnston Outdoor Heat Sink Overheat / Inverter Module Temperature Protection

P3 displayed, compressor speed limited or unit shuts down intermittently

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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 airflow through inverter compartment, Failed inverter cooling fan (if equipped), Poor thermal contact between module and heat sink, High ambient temperature with dirty condenser

How to Fix / Troubleshooting

Safety: Disconnect power at the outdoor disconnect.

  • Inspect inverter compartment: Remove the control panel cover and ensure vents are not blocked by debris or insulation.
  • Check cooling fan: If the inverter uses a dedicated cooling fan, verify it runs when the unit operates. Replace if failed.
  • Clean condenser: Improve overall heat rejection by cleaning the condenser coil.
  • Thermal paste: If the inverter module has been serviced before, ensure proper mounting and thermal compound between module and heat sink (technician task).
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Repair Difficulty

Hard 4/5

Required Part

Inverter Cooling Fan
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