H1
Rheem Defrost Protection / Outdoor Coil Frost Overload

Rheem inverter system shows H1 and may stop heating; defrost cycles may be abnormal.

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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

Outdoor coil heavily frosted due to low airflow, Failed defrost sensor, Defrost control logic error on outdoor PCB, Low refrigerant charge causing coil to freeze

How to Fix / Troubleshooting

Safety first: Turn off power before inspecting the outdoor unit in freezing conditions.

  • Check coil frosting: Inspect the outdoor coil. A light frost is normal; a solid block of ice is not. Clear snow and debris from around the unit.
  • Verify fan operation: Ensure the outdoor fan runs during heating mode (except during defrost). Replace the fan motor if inoperative.
  • Sensor check: Inspect the outdoor coil thermistor used for defrost. Ensure it is attached and wired correctly.
  • Professional service: If H1 persists, a technician should verify defrost operation, sensor readings, and refrigerant charge.

Warning: Do not chip ice off the coil with sharp tools; this can puncture tubing.

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Repair Difficulty

Hard 4/5

Required Part

Rheem Outdoor Coil Thermistor / Outdoor Control Board
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