Daikin Air Conditioner Error AJ

⚡ Quick Answer: The Daikin air conditioner error AJ indicates a communication failure between the indoor and outdoor units, often caused by an incorrect or missing ca... ✅ DIY Fixable

What Does Error AJ Mean?

The Daikin air conditioner error AJ indicates a communication failure between the indoor and outdoor units, often caused by an incorrect or missing capacity setting adaptor or a fault in the indoor unit's PCB configuration. This error typically results in the unit stopping operation or showing reduced performance, alongside the error code AJ being displayed on the indoor unit or through diagnostic tools.

Common Symptoms:

  • Unit may stop operating or show reduced performance
  • Error code AJ displayed on indoor unit or via remote/diagnostic tool

Possible Causes

  • Incorrect or missing capacity setting adaptor installation (medium)
  • Indoor unit printed circuit board (PCB) configuration or component fault (medium)

How to Fix Error AJ

DIY Fix Check for basic reset and consult installer/support

  1. Turn off the unit using the remote or main power switch.
  2. Wait a few minutes then restore power and attempt restart.
  3. If the error persists, contact your installing dealer or Daikin support with the code AJ.

Technician Only Inspect and correct capacity setting adaptor and PCB configuration

  1. Power down the air conditioner at the breaker.
  2. Access the indoor unit control PCB and verify the capacity/adaptor installation and address settings according to service manual.
  3. Check the adaptor connection integrity and seating.
  4. Test or replace the PCB if misconfiguration or fault is confirmed per diagnostic procedures.

Parts needed: Capacity setting adaptor, Indoor unit PCB

🛑 When to Call a Pro:
  • If AJ persists after basic power reset
  • If you cannot confirm adaptor installation/configuration
  • If frequent recurrence of the error occurs

Technical Specifications

wattage N/A
component Control Board
resistance N/A
part_number DAIKIN 4B203A1
voltage_rating 230V AC

Common Questions

What does AJ error mean on daikin air conditioner?

AJ error indicates a communication failure between indoor and outdoor units, often leading to reduced performance.

Can I fix daikin air conditioner AJ error myself?

Yes, you can perform a basic reset by turning off the unit, waiting a few minutes, and restarting it.

How much does it cost to fix AJ error?

Repair costs are moderate and depend on the need for PCB or adaptor replacements.

When should I call a technician for AJ?

Call a technician if the AJ error persists after a reset or if you cannot confirm the adaptor installation.

Sources & References

Data last verified: 2026-07-01

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