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

  1. Turn off the air conditioner using remote or power switch
  2. Disconnect power at breaker or unplug for ~1 minute
  3. Restore power and restart unit
  4. Check if C4 error persists

Technician Only Inspect and repair thermistor circuit

  1. Disconnect power and open indoor unit
  2. Locate indoor heat exchanger thermistor on liquid pipe/coil
  3. Check thermistor resistance with a multimeter against Daikin specifications
  4. Inspect wiring harness and connector integrity
  5. Replace thermistor if open/short or out of specification
  6. 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)

🛑 When to Call a Pro:
  • If error persists after reset and basic inspection
  • If you are not trained in handling electrical components
  • If thermistor/PCB replacement is required

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

Data last verified: 2026-07-01

User Comments (0)

Share your experience or solution below.

Be the first to comment!