Daikin Aircon HJ Error Code
Use this Daikin HJ error code guide to capture the fault correctly and see what should be checked before parts are quoted.
What does Daikin HJ mean?
Daikin HJ is listed as malfunction of thermal storage tank water level in Ceiling Cassette, Ceiling Suspended, Inverter Split rows such as General RA self-diagnosis guide, SkyAir. The loaded row is source-backed by official diagnostic material. Confirm the exact model, series, or signal row before accepting a parts quote.
Low or interrupted water flow through the hydro-kit circuit.
Flow switch, water-temperature sensor, pump, strainer, or valve fault.
Freeze or overtemperature protection caused by water-side or control conditions.
What to do now
Use these steps before customer action or a parts quote.
Treat it as a fault signal
Stop the affected hydro-kit if HJ returns with low flow, freezing, overheating, or abnormal water temperatures.
No manufacturer reset steps listed for HJ
Capture the complete HJ display and model stickers first. The selected source row lists no customer reset procedure; do not treat a generic power-cycle as manufacturer guidance.
Send these to us
HJ error code, a clear display photo, Daikin model stickers, affected rooms, operating state when the code appeared, and water-flow, pump, valve, and temperature symptoms
Source-specific guidance
These diagnostic-reference notes help match the code to the exact model. Electrical, refrigerant, wiring, resistance, and component checks are technician work, not DIY steps.
| Source detail | What it says |
|---|---|
| Diagnostic note | Stop the system if it smells burnt, leaks, or trips power; note the exact model and code before booking diagnosis. |
| Singapore / model note | Official Daikin SM-TS3 row; use only where the system has thermal-storage tank or matching water-level hardware. |
- Source detail
- Diagnostic note
- What it says
- Stop the system if it smells burnt, leaks, or trips power; note the exact model and code before booking diagnosis.
- Source detail
- Singapore / model note
- What it says
- Official Daikin SM-TS3 row; use only where the system has thermal-storage tank or matching water-level hardware.
What to check before repair
Use this split to separate safe evidence capture from the tests a technician should prove before quoting parts.
| You can check | Technician should confirm |
|---|---|
| Before taking any system action on HJ, take a clear display photo. | Confirm which hydro-kit water circuit or protection HJ identifies. |
| Capture the Daikin indoor and outdoor model stickers so the correct family row is used. | Measure water flow and temperature, then check the pump, strainer, valves, flow switch, and named sensor. |
| The selected source row lists no customer reset procedure. Note whether one room, several rooms, or the whole system is affected. | Confirm freeze, overtemperature, wiring, and controller conditions before replacing hydro-kit parts. |
- You can check
- Before taking any system action on HJ, take a clear display photo.
- Technician should confirm
- Confirm which hydro-kit water circuit or protection HJ identifies.
- You can check
- Capture the Daikin indoor and outdoor model stickers so the correct family row is used.
- Technician should confirm
- Measure water flow and temperature, then check the pump, strainer, valves, flow switch, and named sensor.
- You can check
- The selected source row lists no customer reset procedure. Note whether one room, several rooms, or the whole system is affected.
- Technician should confirm
- Confirm freeze, overtemperature, wiring, and controller conditions before replacing hydro-kit parts.
What changes the next step
These clues decide whether the first check is room-side, shared outdoor-side, refrigerant-side, source-table, or model-family confirmation.
| What you see | What it points to |
|---|---|
| Only one indoor unit shows HJ. | The affected room, indoor board path, wiring route, or local component should be checked first. |
| Several rooms or the outdoor unit show the same HJ fault. | Prioritise the shared outdoor side, power path, and source-listed system branch. |
| The hydro-kit reports low flow, freezing, overheating, or abnormal water temperature. | Water flow, pump, strainer, valves, switches, and sensors should be checked before the hydro-kit returns to operation. |
| The model family is different from the row you found online. | Use the model or series filter first; same-looking codes can still belong to different diagnostic tables. |
| The model belongs to Ceiling Cassette, Ceiling Suspended, Inverter Split rows such as General RA self-diagnosis guide, SkyAir. | The loaded row is source-backed by official diagnostic material. Use the matching source row before quoting parts. |
- What you see
- Only one indoor unit shows HJ.
- What it points to
- The affected room, indoor board path, wiring route, or local component should be checked first.
- What you see
- Several rooms or the outdoor unit show the same HJ fault.
- What it points to
- Prioritise the shared outdoor side, power path, and source-listed system branch.
- What you see
- The hydro-kit reports low flow, freezing, overheating, or abnormal water temperature.
- What it points to
- Water flow, pump, strainer, valves, switches, and sensors should be checked before the hydro-kit returns to operation.
- What you see
- The model family is different from the row you found online.
- What it points to
- Use the model or series filter first; same-looking codes can still belong to different diagnostic tables.
- What you see
- The model belongs to Ceiling Cassette, Ceiling Suspended, Inverter Split rows such as General RA self-diagnosis guide, SkyAir.
- What it points to
- The loaded row is source-backed by official diagnostic material. Use the matching source row before quoting parts.
Water-flow or hydro-kit control decision
Daikin HJ needs measured water flow, temperature, pump, valve, switch, and sensor evidence before hydro-kit parts are approved.
A blocked strainer, closed valve, or low-flow condition can trigger protection without a failed control board.
Flow-switch and water-sensor replacement should follow measured checks.
Freeze or overtemperature events need the underlying water-circuit cause corrected before reset.
Daikin HJ questions
What does the Daikin HJ error mean?
Can I fix a Daikin HJ error myself?
Is it safe to keep running the aircon with an HJ error?
What causes a Daikin HJ error?
Will a Daikin HJ error need a repair or a full replacement?
What should I send a technician about a Daikin HJ error?
Confirm the fault
Share the error code, model number and symptoms so we can assess the likely cause.
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Browse the full Daikin list or check a few codes in the same fault category.
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Read next
Use these if the quote mentions the parts, checks, or repair path this code points to.