c4
Moderate
Daikin · Mini-Splits & Ductless Systems
Heat Exchanger Temperature Sensor Fault
Quick Answer
Error code C4 on your Daikin Mini-Splits & Ductless Systems means: Heat Exchanger Temperature Sensor Fault. This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
Likely Causes
How to Fix It
1
Locate the heat exchanger thermistor on the indoor coil and check its mounting
2
Measure the thermistor resistance with a multimeter and compare to the Daikin resistance chart
3
Check the connector at the indoor PCB for corrosion or loose pins
4
Replace the thermistor if resistance is out of specification for the current temperature
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Heat exchanger thermistor
Thermistor mounting clip
Wire connectors
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