H3
Pioneer Compressor Overload / Overcurrent Protection

Indoor unit shows H3 and system shuts down under heavy cooling load

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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

High head pressure from dirty condenser, Overcharged refrigerant, Failing compressor, Inverter module current sensing fault

How to Fix / Troubleshooting

Safety first: Turn off power at the outdoor disconnect. Do not bypass overload protections.

Steps to try:

  • Clean outdoor coil thoroughly: Use coil cleaner and water to restore heat rejection.
  • Check for airflow restrictions: Ensure adequate clearance around the outdoor unit and that nothing is blocking discharge air.
  • Inspect wiring: Look for burnt or loose connections at the compressor terminals and inverter board (with power off).
  • Restart after cool-down: Allow the unit to cool for at least 30 minutes before restarting.

When to call a pro: H3 usually requires measurement of compressor current and system pressures by a technician.

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Repair Difficulty

Professional Required 5/5

Required Part

Rotary/Scroll Compressor
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