H1
Sharp Defrost or Heating Mode Protection / Low Outdoor Temperature Lockout

Heat pump models: unit does not start heating; H1 displayed.

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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, Defrost sensor misreading, Defrost control malfunction on outdoor PCB, Extremely low ambient temperature below operating range

How to Fix / Troubleshooting

Safety first: Turn off power before touching the outdoor unit or coil.

  • Check outdoor coil: Inspect for heavy ice buildup. If the coil is completely iced, allow the unit to defrost naturally by turning it off, or use warm (not hot) water to melt ice. Do not chip ice with tools.
  • Clear drainage: Ensure the outdoor base pan drain holes are not blocked so defrost water can escape.
  • Defrost sensor: Verify the outdoor coil thermistor is properly attached and replace if faulty.
  • Operating limits: Confirm that outdoor temperature is within Sharp’s specified heating range. Below this, H1 or similar protection may prevent operation.
  • PCB / defrost logic: If the unit never enters proper defrost or frequently shows H1, the outdoor PCB may require replacement by a technician.
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Repair Difficulty

Hard 4/5

Required Part

Outdoor Coil Thermistor
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