Daikin Aircon AJ Error Code
Daikin AJ points to malfunction of capacity setting on indoor unit PCB. The source is official, but the exact model or series still decides the applicable row.
What Does Daikin AJ Mean?
Daikin AJ is listed as malfunction of capacity setting on indoor unit PCB in Ceiling Cassette, Ceiling Suspended, Residential Ducted rows such as SkyAir, VRV. The loaded row is source-backed by official diagnostic material. Confirm the exact model, series, or signal row before accepting a parts quote.
Indoor or outdoor PCB fault recorded by the source table.
Power supply, connector, fuse, EEPROM, or board-input problem.
Water ingress, surge damage, or wiring issue that must be ruled out before board replacement.
What To Do Now
Use these steps before another reset or parts quote.
Stop using the unit if AJ returns
If AJ returns after one reset, stop repeated restarts and get the matching source row diagnosed.
Reset AJ once
Capture the AJ display first, then power-cycle once only and note whether the same fault returns.
Send these to us
AJ error code, a clear display photo, Daikin model stickers, affected rooms, and reset result
Send Us What You're Seeing
Share AJ, your Daikin model, and what happened before it appeared. We'll read it and respond with the right next step before any work is approved.
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 resetting AJ, take a clear display photo. | Confirm which PCB or board input AJ points to on the source row. |
| Capture the Daikin indoor and outdoor model stickers so the correct family row is used. | Check power supply, fuses, connectors, wiring, and board indicators. |
| Note whether one room, several rooms, or the whole system is affected, plus whether it returns after one reset. | Rule out water ingress, surge damage, and connected component faults before replacing the board. |
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 AJ. | The affected room, indoor board path, wiring route, or local component should be checked first. |
| Several rooms or the outdoor unit show the same AJ fault. | The shared outdoor side, power path, communication trunk, or refrigerant circuit needs priority checking. |
| The fault returns immediately after one reset. | Start with the source-row diagnostic branch before approving parts. |
| 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, Residential Ducted rows such as SkyAir, VRV. | The loaded row is source-backed by official diagnostic material. Use the matching source row before quoting parts. |
PCB Repair Or Replacement Decision
Daikin AJ should not jump straight to board replacement. Confirm power, connectors, wiring, and connected parts before deciding whether PCB repair or replacement is justified.
Power, fuse, connector, and water-ingress checks should happen before board replacement.
Connected motors, sensors, or valves can damage or confuse a PCB diagnosis.
Board availability and system age decide whether replacement is sensible.
Read Next
Use these if the quote mentions the parts, checks, or repair path this code points to.
Other Daikin Error Codes
If the code you're seeing isn't AJ, jump to one of these or browse the full Daikin list.
Ready to Get Started?
Send the AJ error code, a clear display photo, and Daikin model sticker. Send the model sticker so the matching official row can be checked quickly. We can help check whether this is a status row or an active fault.