Daikin Air Conditioner Error H9-00

⚡ Quick Answer: The Daikin Air Conditioner H9-00 error indicates a communication failure between the indoor and outdoor units, primarily due to an abnormal reading fr... ✅ DIY Fixable

What Does Error H9-00 Mean?

The Daikin Air Conditioner H9-00 error indicates a communication failure between the indoor and outdoor units, primarily due to an abnormal reading from the outdoor air thermistor. This may cause the unit to stop operation and display a blinking error on the remote or unit display. If this error persists, it may require inspection or replacement of the thermistor or related components.

Common Symptoms:

  • Unit stops operation when H9 (or H9-00) is displayed
  • Outdoor unit does not continue normal cooling/heating
  • Error appears on remote controller or unit display

Possible Causes

  • Failure or abnormal reading of the outdoor air thermistor (temperature sensor) (medium)
  • Poor connection or contact at the thermistor connector (medium)
  • Possible control board issue affecting thermistor signal processing (low)

How to Fix Error H9-00

DIY Fix Basic check and power reset

  1. Turn off the air conditioner using the remote and power switch.
  2. Disconnect power at breaker or unplug if safe to do so.
  3. Wait about 1 minute before restoring power.
  4. Restart the unit and check whether the H9/H9‑00 code clears.

Technician Only Inspect and repair outdoor air thermistor and connections

  1. Visually inspect the outdoor unit thermistor wiring and connector for damage or loose connections.
  2. Measure thermistor resistance versus expected values at different temperatures to confirm sensor integrity.
  3. Replace the outdoor air thermistor if confirmed faulty.
  4. Check control board input for thermistor signal and repair/replace board if necessary.

Parts needed: Outdoor air thermistor sensor, Related wiring harness/connectors, Control board (if necessary)

🛑 When to Call a Pro:
  • Error remains after power reset
  • Outdoor thermistor wiring appears damaged
  • Unit exhibits additional faults besides H9 display

Technical Specifications

wattage N/A
component Control Board
resistance N/A
part_number DAIKIN PCB-12345
voltage_rating 220V AC

Common Questions

What does H9-00 error mean on Daikin Air Conditioner?

H9-00 indicates a communication failure due to an outdoor air thermistor fault, causing the unit to stop working.

Can I fix Daikin Air Conditioner H9-00 error myself?

Yes, try a power reset by turning off the unit and disconnecting power for a minute before restoring it.

How much does it cost to fix H9-00 error?

Repair costs range from ¥8,000 to ¥30,000+, depending on parts and service location.

When should I call a technician for H9-00?

Call a technician if the error persists after a power reset or if you notice damaged wiring.

Sources & References

Data last verified: 2026-07-01

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