Daikin mini_split Error Code H9

What does H9 mean?

Outdoor air temperature sensor reading is out of range — sensor failure or environmental issue.

Common causes

• Failed outdoor ambient thermistor
• Extreme ambient temperature beyond sensor range
• Damaged sensor lead wire

Diagnostic & testing steps

1. 1. Measure outdoor ambient temp with separate thermometer
2. 2. Compare to thermistor resistance chart: ~10K ohms at 77°F
3. 3. Check thermistor connector for corrosion or loose connection
4. 4. Replace thermistor if resistance is open or shorted

Tools required

• Multimeter
• Thermometer

OEM parts & part numbers

Outdoor Ambient Thermistor

Part numbers: 2503234