Daikin Air Conditioner Error C9
⚡ Quick Answer: The Daikin Air Conditioner C9 error indicates a communication failure between the indoor and outdoor units, primarily due to a fault in the indoor uni... ✅ DIY Fixable
What Does Error C9 Mean?
The Daikin Air Conditioner C9 error indicates a communication failure between the indoor and outdoor units, primarily due to a fault in the indoor unit's suction air temperature sensing system. This can result from a malfunctioning suction air thermistor, poor wiring connections, or issues with the indoor unit's control PCB. When this error occurs, the air conditioner may stop operating and fail to produce cool or warm air, often accompanied by a flashing display.
Common Symptoms:
- Indoor unit stops operation when C9 displays
- Air conditioner may not produce cool/heat air
- Error code displayed on remote or unit indicating sensor fault
Possible Causes
- Faulty suction air thermistor (high)
- Poor connection or wiring issue at the thermistor connector (medium)
- Indoor unit control PCB processing error of thermistor signal (medium)
How to Fix Error C9
DIY Fix Basic power reset and check environmental conditions
- Turn off the air conditioner and cut power at the breaker or unplug the unit
- Wait approximately 1 minute
- Restore power and attempt to restart to see if the error clears
- Ensure air intake and filters are clean and unobstructed
Technician Only Inspect and replace suction air thermistor and associated wiring
- Disconnect power to the unit
- Remove indoor unit cover to access suction air thermistor
- Test thermistor resistance and verify against spec
- Check and secure thermistor connector and wiring integrity
- Replace thermistor if out of specification
- If thermistor and wiring are correct, test and inspect indoor control PCB for faults
Parts needed: Suction air thermistor, Thermistor wiring/connector, Indoor unit PCB (if required)
- If the error persists after basic power reset and cleaning
- If thermistor or PCB testing tools are not available to the technician
- If signs of electrical damage are present
Next step
Choose the next step for C9
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
Thermistor
Measures precise temperature changes and sends resistance feedback to the control board.
- 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 | N/A |
|---|---|
| component | Control Board |
| resistance | N/A |
| part_number | DAIKIN 4A118A |
| voltage_rating | 230V AC |
Common Questions
What does C9 error mean on Daikin Air Conditioner?
C9 indicates a communication failure linked to a faulty suction air thermistor, causing the unit to stop working.
Can I fix Daikin Air Conditioner C9 error myself?
Yes, you can try a basic power reset by turning off the unit and restoring power after one minute.
How much does it cost to fix C9 error?
Repair costs typically range from $50 to $300+, depending on parts and labor.
When should I call a technician for C9?
Call a technician if the error persists after a reset, or if you lack the tools for testing components.
Sources & References
- Skycon Air – Daikin C9 Error Explanation (community)
- AirconLand – Daikin C9 Error Code (community)
Data last verified: 2026-07-22
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