CodeRegistry
Brands
  1. Home
  2. Daikin
  3. ASHP Error Codes
  4. AJ-03
About·Privacy·Terms

CodeRegistry — Your global library for technical solutions.

For your safety: always follow the equipment manufacturer’s official manuals. CodeRegistry is an independent help site and is not affiliated with the brands listed here.

AJ-03

AJ-03 — Too long DHW heat-up time required

Daikin · ASHP Error Codes

What does AJ-03 mean?

The unit is taking an excessively long time to heat domestic hot water (DHW).

Common Causes

  • Low incoming water temperature
  • Heating element or heat exchanger issue
  • Reduced refrigerant charge

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check the temperature of the incoming water supply.

  2. 2

    Ensure the unit is sized correctly for the hot water demand.

  3. 3

    Inspect the heat exchanger for scale buildup.

  4. 4

    A technician should verify refrigerant levels and heating components.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

7H-017H-01 — Water flow problem7H-047H-04 — Water flow problem during domestic hot water production7H-057H-05 — Water flow problem during heating/sampling
Source: Daikin ASHP Error Codes
Open Manual (Page 2)Search more codes in this manual