Daikin Air Conditioner Error C4
⚡ Quick Answer: The Daikin Air Conditioner C4 error indicates a communication failure between the indoor and outdoor units, often due to an abnormal heat exchanger te... ✅ DIY Fixable
What Does Error C4 Mean?
The Daikin Air Conditioner C4 error indicates a communication failure between the indoor and outdoor units, often due to an abnormal heat exchanger temperature sensor (thermistor) issue. Symptoms include the unit stopping operation and detected abnormal resistance in the thermistor circuit, leading to an unresponsive system.
Common Symptoms:
- Unit stops operation when C4 appears
- Thermostat related to indoor heat exchanger temperature anomaly
- Detected abnormal resistance in heat exchanger thermistor circuit
Possible Causes
- Indoor heat exchanger liquid pipe thermistor fault (open/short or abnormal resistance) (high)
How to Fix Error C4
DIY Fix Basic reset procedure
- Turn off the air conditioner using remote or power switch
- Disconnect power at breaker or unplug for ~1 minute
- Restore power and restart unit
- Check if C4 error persists
Technician Only Inspect and repair thermistor circuit
- Disconnect power and open indoor unit
- Locate indoor heat exchanger thermistor on liquid pipe/coil
- Check thermistor resistance with a multimeter against Daikin specifications
- Inspect wiring harness and connector integrity
- Replace thermistor if open/short or out of specification
- Check indoor PCB thermistor signal circuits and repair/replace PCB if required
Parts needed: Indoor heat exchanger thermistor, Wiring harness/connector, Indoor unit PCB (if needed)
- If error persists after reset and basic inspection
- If you are not trained in handling electrical components
- If thermistor/PCB replacement is required
Next step
Choose the next step for C4
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.
Wiring Harness
Connects controls, sensors, motors, and other electrical components inside the appliance.
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 4E-2E-1A |
| voltage_rating | 220V AC |
Common Questions
What does C4 error mean on Daikin Air Conditioner?
C4 indicates a communication failure often linked to a thermistor fault affecting the indoor unit.
Can I fix Daikin Air Conditioner C4 error myself?
Yes, you can perform a basic reset by turning off the unit and restoring power after a minute.
How much does it cost to fix C4 error?
Repair costs range from $150 to $300+, including parts and labor.
When should I call a technician for C4?
Call a technician if the error persists after a reset or if you are not trained to handle electrical components.
Sources & References
- Daikin C4 Error Code: Ultimate Guide - Silverback Air‑con (community)
- C4 | Skycon Air Pty Ltd (community)
Data last verified: 2026-07-22
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