Daikin Error Code C4: Heat Exchanger Thermistor Fault
Warning: Your Daikin HVAC system has detected a potential issue with the heat exchanger thermistor. It's safe to continue using the system, but a professional repair is recommended.
How to Fix Daikin Code C4
- Check if the thermostat is set to the correct mode and temperature
- Turn off the system and turn it back on after a few minutes to see if the error clears
- Contact a professional HVAC technician for repair
How to Reset Daikin Code C4
- Turn off the unit using the remote control or wall controller.
- Turn off the circuit breaker for the outdoor and indoor units. Wait 60 seconds.
- Restore power at the breaker.
- Turn the unit on with the remote control. If the error returns, the fault needs professional diagnosis.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Daikin Error Code C4 Mean?
The Daikin C4 error code indicates a fault with the heat exchanger thermistor. This component measures the temperature of the heat exchanger, which is crucial for maintaining the correct temperature in your home. If the thermistor fails, your HVAC system may not function correctly, leading to comfort issues and potentially causing the system to shut down. This error is typically caused by a faulty thermistor, but it could also be due to a wiring issue or a problem with the control board.
Common Causes
- Faulty heat exchanger thermistor
- Wiring issue between the thermistor and control board
- Problem with the control board
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| System is not heating or cooling properly | Measure the resistance of the heat exchanger thermistor using a multimeter | Resistance should match the manufacturer's specifications (usually around 10kΩ ±20%) |
| Thermistor resistance is out of range | Inspect the wiring between the thermistor and the control board for any breaks or corrosion | Wiring should be intact and clean |
Applicable Daikin Models
- Daikin Comfort(electric)
- Daikin Fit(electric)
- Daikin Intelligent Touch(electric)
- Daikin Latitude(electric)
- Daikin Unitary System(electric)
- FIT(electric)
- Inverter Ducted Split System(electric)
- LV Series(electric)
- MXS(electric)
- Multi-Zone(electric)
- NCB(electric)
- NCM(electric)
- NCV(electric)
- NCW(electric)
- NMB(electric)
- NMP(electric)
- NPE(electric)
- NTV(electric)
- NW(gas)
- NWZ(dual_fuel)
- Quaternity(electric)
- SkyAir(electric)
- VRV(electric)
- VRV IV(electric)
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Heat Exchanger Thermistor | 4000012000 | — | Find Part |
Related Codes on Same Models
Other codes that affect the same Daikin model families as C4.
| Code | Description | Severity |
|---|---|---|
| A1 | Indoor PCB Defective | Warning |
| A3 | Drain Level System Fault | Warning |
| A5 | Freeze-Up/Overheat Protection | Warning |
| A6 | Fan Motor Lock/Overcurrent | Warning |
| C9 | Suction Air Thermistor Fault | Warning |
| E1 | Outdoor PCB Defective | Warning |
| E3 | High Pressure Switch Activated | Warning |
| E4 | Low Pressure Switch Activated | Warning |
| E5 | Compressor Motor Lock | Warning |
| E6 | Standard Compressor Motor | Warning |