H3
Day & Night Compressor Overload / Thermal Protection Lockout

H3 code, compressor locked out, unit may run fan only

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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 outdoor coil, Non-running outdoor fan, Extremely high ambient temperature, Failing compressor drawing excessive current, Incorrect refrigerant charge

How to Fix / Troubleshooting

Safety first: Turn OFF power at the outdoor disconnect. Do not bypass any safety devices.

  • Step 1 – Allow cool-down: Let the unit sit powered OFF for at least 30–60 minutes to allow the compressor internal overload to reset.
  • Step 2 – Clean and clear coil: Clean the condenser coil and ensure adequate airflow around the unit.
  • Step 3 – Verify fan operation: After restoring power, confirm the outdoor fan starts and runs continuously when the compressor is called.
  • Step 4 – Monitor operation: If H3 returns quickly, shut the system down and call a technician to check compressor health and refrigerant pressures.
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Repair Difficulty

Hard 4/5

Required Part

Compressor
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