Daikin Mini Split Error Code HJ: How to Fix It

Medium 30-60 minutes Medium Severity Verified June 2026
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Error Code
HJ
Brand
Daikin
Product Type
mini_split
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30-60 minutes
Error code HJ on your Daikin mini split indicates a fault in the tank thermistor. The thermistor monitors the temperature of the refrigerant tank (accumulator). A faulty reading or connection can stop your system from operating properly. This guide walks you through checking wiring, testing the thermistor, and replacing it if necessary.
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Tools You'll Need

How to Fix Error Code HJ

  1. Power Off the Unit

    Always disconnect power before opening the unit. Capacitors can hold a dangerous charge.

  2. Locate the Tank Thermistor

  3. Inspect Wiring and Connections

    Be careful not to touch any live components even after power-off.

  4. Test the Thermistor with a Multimeter

  5. Replace the Thermistor if Faulty

    Ensure the replacement thermistor matches the resistance curve of the original.

  6. Power On and Test

Parts You May Need

Daikin tank thermistor (10kΩ at 25°C)
Check Price on Amazon
Daikin tank thermistor (10kΩ at 25°C)
Check Price on Amazon
Daikin tank thermistor (10kΩ at 25°C)
Check Price on Amazon
Daikin tank thermistor (10kΩ at 25°C)
Check Price on Amazon
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When to Call a Professional

If you've replaced the thermistor and the error persists, or if you're uncomfortable working with electrical components, contact a certified HVAC technician. Issues with the main control board require professional diagnosis.

Frequently Asked Questions

What does error code HJ mean on a Daikin mini split?
Error code HJ indicates a tank thermistor fault. The thermistor is a temperature sensor on the refrigerant accumulator. It may be faulty, disconnected, or have a wiring issue.
Can I run my Daikin AC with error code HJ?
It is not recommended. The system may not operate correctly, and continued use could lead to further damage. It's best to troubleshoot and fix the issue promptly.
How do I test the tank thermistor on my Daikin unit?
Use a multimeter set to resistance. Disconnect the thermistor and measure its resistance. At room temperature, it should be around 10-15kΩ. If it reads open or shorted, replace it.
Where is the tank thermistor located on a Daikin mini split?
The tank thermistor is usually attached to the accumulator (a large cylindrical tank) in the outdoor unit. It may be secured with a metal clip and have two wires leading to the control board.
Do I need a specific Daikin part for the thermistor replacement?
While a genuine Daikin thermistor is recommended, generic thermistors with the same resistance curve (e.g., 10kΩ at 25°C) can work. Check your unit's specifications or consult a technician.

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