c9
Easy Fix
Daikin · Mini-Splits & Ductless Systems
Room Temperature Sensor Fault
Quick Answer
Error code C9 on your Daikin Mini-Splits & Ductless Systems means: Room 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 room temperature sensor on the indoor unit (typically near the return air intake)
2
Measure the thermistor resistance and compare to the expected value for room temperature
3
Check the connector at the indoor PCB and reseat if loose
4
Inspect the sensor wire for pinching or damage within the indoor unit housing
5
Replace the room temperature sensor if resistance is out of specification
Pro Tip
This is a common issue that most users can resolve without specialized tools. Try the first step before moving on to more complex solutions.
Parts You May Need
Room temperature thermistor
Wire connectors
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