Daikin Air Conditioner Error C9-00
⚡ Quick Answer: The Daikin Air Conditioner C9-00 error indicates a communication failure with the compressor, typically caused by an abnormality in the indoor unit's ... ✅ DIY Fixable
What Does Error C9-00 Mean?
The Daikin Air Conditioner C9-00 error indicates a communication failure with the compressor, typically caused by an abnormality in the indoor unit's suction air temperature thermistor (sensor). This malfunction leads to the unit stopping operation and may prevent the indoor fan or cooling from functioning, resulting in an error message on the remote or control panel.
Common Symptoms:
- Unit stops operation when code appears
- Indoor fan or cooling operation may stop
- Error displayed via remote or control panel
Possible Causes
- Faulty suction air temperature thermistor (sensor) (high)
- Thermistor wiring or connector issues (medium)
- Indoor unit PCB processing/signal fault (medium)
How to Fix Error C9-00
DIY Fix Basic checks and power reset
- Stop unit operation
- Turn off AC and disconnect power (unplug or breaker)
- Wait ~1 minute
- Restore power and attempt restart
Technician Only Inspection and repair of thermistor circuit
- Inspect the suction air thermistor for proper function using diagnostic tools
- Check wiring harness, connectors for continuity and secure attachment
- Test/replace the thermistor if defective
- Inspect indoor unit PCB for signal processing faults and repair/replace as needed
Parts needed: Suction air thermistor (indoor air temperature sensor), Connecting wires and connectors, Indoor unit PCB (if required)
- After basic power reset and error persists
- If you are uncomfortable performing electrical or internal checks
Next step
Choose the next step for C9-00
Confirm the diagnosis before ordering. An error code can identify the system involved, but it does not prove that a specific part has failed.
Most relevant component to inspect
Temperature Sensor
Monitors the internal temperature to ensure correct operation and prevent overheating.
- Typical part-only price
- $15 - $35
- DIY difficulty
- Easy
- Estimated time
- 15-30 mins
Where can I find the model number?
Check the rating label around the door, lid, frame, rear panel, or inside the appliance cabinet. Use the complete model number, including suffixes.
Verify the complete model and part number on the retailer's compatibility page before ordering.
Other parts options
Check related components first; use model search as a fallback.
HVAC Control Board
Controls fan, compressor, sensor, and communication functions in the HVAC unit.
Model-compatible Air Conditioner parts
Enter the complete model number to browse compatible replacement parts. This is a model-based parts search, not a diagnosis that a specific component failed.
Affiliate disclosure: As an Amazon Associate I earn from qualifying purchases. We may earn a commission from other qualifying purchases or service requests made through links on this page, at no additional cost to you. Recommendations are based on repair relevance, not commission rate.
Optional routine care
Maintenance supplies
These products support cleaning or routine upkeep. They are separate from the possible repair components above and are not claimed to fix this error code or symptom.
Air Conditioner Fin Cleaner
For routine cleaning of accessible coil fins when permitted by the manufacturer. Disconnect power and follow product and appliance instructions.
Model-Compatible Washable AC Filter
A reusable filter option only where the appliance supports one. Match the full model, dimensions, and filter specification.
Compatibility check required: use the complete appliance model and compare the existing filter, bag, or specification before ordering.
Affiliate disclosure: As an Amazon Associate I earn from qualifying purchases. Recommendations are based on routine-care relevance, not commission rate.
Technical Specifications
| wattage | 3000W |
|---|---|
| component | Compressor Control Board |
| resistance | 3-5 ohms |
| part_number | DAIKIN 4E0B0A |
| voltage_rating | 220V AC |
Common Questions
What does C9-00 error mean on Daikin Air Conditioner?
C9-00 indicates a communication failure with the compressor due to a thermistor fault.
Can I fix Daikin Air Conditioner C9-00 error myself?
Yes, perform a basic power reset by turning off the AC and disconnecting power for a minute.
How much does it cost to fix C9-00 error?
Repair costs range from $100 to $400+, depending on parts and labor.
When should I call a technician for C9-00?
Call a technician if the error persists after a power reset or if you're uncomfortable with electrical checks.
Sources & References
Data last verified: 2026-07-22
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