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Daikin Aircon UA Error Code

Use this Daikin UA error code guide to confirm the source table meaning, capture the reporting equipment and model, and match the service manual before diagnosis. Match the model first; same-looking codes can point to different rows.

What does Daikin UA mean?

Daikin UA is listed as defect of indoor/outdoor power supply, improper combination of indoor and outdoor units, and indoor-outdoor unit combination fault in mixed model-family source rows, including VRV X RXQ-A(N)R cooling only, VRV IV+ REYQ / REMQ heat recovery, VRV 5-S RXYSA R32, VRV 5 Heat Recovery REMA / REYA R32, VRV 5 Heat Pump RYMA / RXYA R32, Sky Air FNA R32 - test-run diagnostic, and ERA-AYF AHU / air curtain. The loaded row is source-backed by official diagnostic material. Do not collapse this code across model families; use the model, series, or system type to choose the right row. Confirm the exact model, series, or signal row before accepting a parts quote.

Choose the matching source row

The same visible code has more than one source-backed meaning. Match the model family, system type, or reporting unit before approving parts.

  • Code
    General RA self-diagnosis guide
    What it means
    Defect of indoor/outdoor power supply
    What to check first
    Match this row to the installed model or reporting unit, then use the source-specific checks below.
  • Code
    Fan Coil
    What it means
    Improper combination of indoor and outdoor units
    What to check first
    Match this row to the installed model or reporting unit, then use the source-specific checks below.
  • Code
    EZi
    What it means
    Indoor-outdoor unit combination fault
    What to check first
    Match this row to the installed model or reporting unit, then use the source-specific checks below.
  • Code
    VRV X RXQ-A(N)R cooling only
    What it means
    Improper indoor-unit, outdoor-unit, or remote-controller combination
    What to check first
    Match this row to the installed model or reporting unit, then use the source-specific checks below.
  • Code
    UA-03 - system
    What it means
    Indoor-unit connection malfunction or refrigerant-type mismatch
    What to check first
    Check other indoor-unit faults and confirm that the indoor-unit mix is allowed. Match the alternating UA-03 display to the system source row.
  • Code
    UA-31 - system
    What it means
    Wrong unit combination in a multi system
    What to check first
    Check whether the unit types are compatible. Match the alternating UA-31 display to the system source row.
  • Code
    UA-20 - system
    What it means
    Wrong outdoor unit connected
    What to check first
    Disconnect the incorrect outdoor unit. Match the alternating UA-20 display to the system source row.
  • Code
    UA-27 - system
    What it means
    No branch-selector unit connected
    What to check first
    Connect the required branch-selector unit. Match the alternating UA-27 display to the system source row.
  • Code
    UA-28 - system
    What it means
    Old branch-selector unit connected
    What to check first
    Disconnect the incompatible branch-selector unit. Match the alternating UA-28 display to the system source row.
  • Code
    UA-53 - system
    What it means
    Branch-selector unit DIP-switch abnormality
    What to check first
    Check the branch-selector unit DIP switches. Match the alternating UA-53 display to the system source row.
  • Code
    VRV 5-S R32 - UA / VRV 5 Heat Recovery R32 - UA / VRV 5 Heat Pump R32 - UA
    What it means
    Connected indoor-unit type or combination mismatch
    What to check first
    Confirm that every connected indoor-unit type is permitted for the system.
  • Code
    Sky Air FNA R32 - UA (test-run diagnostic)
    What it means
    The connected outdoor and indoor units are incompatible
    What to check first
    Confirm the indoor model is FNA25~60A2VEB(9), record the reporting controller, and follow the matching Daikin service procedure.
  • Code
    ERA-AYF AHU / air curtain
    What it means
    Connected-unit type or combination mismatch (UA-03/18/20)
    What to check first
    Match this row to the installed model or reporting unit, then use the source-specific checks below.

What to do now

Use these steps to record evidence and match the installed model to its service manual before diagnosis or a repair quote.

  • Record UA and match the service manual

    Record UA and stop there; the source table gives no customer reset procedure. Arrange diagnosis with the matching service manual.

  • No manufacturer reset steps listed for UA

    Capture the complete UA error code and model stickers first. The source table lists the meaning but no customer reset procedure; do not treat a generic power-cycle as manufacturer guidance.

  • Send these to us

    UA error code, a clear display photo, Daikin indoor and outdoor model stickers, the controller, gateway, or unit that reported the code, operating mode and affected area, and any power or setting changes made after the code appeared

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
    Singapore / model note
    What it says
    Official Daikin SM-TS3 row; this is separate from UA combination faults in model-family manuals.
  • Source detail
    Singapore / model note
    What it says
    Official Daikin SM-TS3 self-diagnosis row. Manual causes: Excess connected indoor units; Defective outdoor unit PCB; Indoor and outdoor refrigerant type mismatch.
  • Source detail
    Singapore / model note
    What it says
    This row is taken from the selected Daikin operation manual's remote-controller fault diagnosis table.

What to check before repair

The source table establishes the code meaning, not a repair procedure. Capture evidence first; model-specific tests belong to the matching service manual.

  • You can check
    Photograph the complete UA error code before taking any action.
    Technician should confirm
    Confirm UA exactly and record which controller, gateway, or unit reported it.
  • You can check
    Capture the Daikin indoor and outdoor model stickers and identify which controller or unit reported it.
    Technician should confirm
    Match the indoor and outdoor model stickers, installed family, and reporting equipment to the source scope.
  • You can check
    The source table provides no customer reset procedure. Preserve the evidence and use the matching service manual for any system action.
    Technician should confirm
    Follow the matching service-manual procedure and keep measured test evidence before naming a failed part.

Source-bounded repair decision

Daikin UA confirms the source-table fault label, not a failed part or repair procedure. Match the installed model to its service manual and require measured diagnostic evidence before approving parts, settings, or refrigerant work.

  • Whether the reporting controller or unit and exact installed model are confirmed.

  • What the matching service-manual procedure and measured tests show.

  • Whether the proposed repair names the evidence for the failed part or condition.

Daikin UA questions

What does the Daikin UA error mean?
Daikin UA is listed as defect of indoor/outdoor power supply, improper combination of indoor and outdoor units, and indoor-outdoor unit combination fault in mixed model-family source rows, including VRV X RXQ-A(N)R cooling only, VRV IV+ REYQ / REMQ heat recovery, VRV 5-S RXYSA R32, VRV 5 Heat Recovery REMA / REYA R32, VRV 5 Heat Pump RYMA / RXYA R32, Sky Air FNA R32 - test-run diagnostic, and ERA-AYF AHU / air curtain. The loaded row is source-backed by official diagnostic material. Do not collapse this code across model families; use the model, series, or system type to choose the right row. Confirm the exact model, series, or signal row before accepting a parts quote.
Can I fix a Daikin UA error myself?
No. UA needs a technician's measurement before parts are decided. Photograph the complete UA error code before taking any action. Capture the Daikin indoor and outdoor model stickers and identify which controller or unit reported it.
Is it safe to keep running the aircon with a UA error?
Record UA and stop there; the source table gives no customer reset procedure. Arrange diagnosis with the matching service manual.
What causes a Daikin UA error?
Daikin UA has source-backed wording that depends on the exact model, source row, or reporting unit. Use the decoder on this page before assuming a specific cause.
Will a Daikin UA error need a repair or a full replacement?
Daikin UA confirms the source-table fault label, not a failed part or repair procedure. Match the installed model to its service manual and require measured diagnostic evidence before approving parts, settings, or refrigerant work.
What should I send a technician about a Daikin UA error?
Before booking, send: UA error code, a clear display photo, Daikin indoor and outdoor model stickers, the controller, gateway, or unit that reported the code, operating mode and affected area, and any power or setting changes made after the code appeared.

Confirm the fault

Share the error code, model number and symptoms so we can assess the likely cause.

Not the right code?

Browse the full Daikin list or check a few codes in the same fault category.

Ready to get started?

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Read next

Use this quote-check guide only after the matching service manual identifies the diagnostic path.