Fujitsu General Technical Reference
Legacy Error Codes and Diagnostic Reference
Earlier split, ducted, cassette and VRF systems
Model-specific fault codes, LED patterns and thermistor reference values
This reference supports field technicians diagnosing earlier Fujitsu General systems. Because fault displays vary by model family, always identify the complete indoor and outdoor model numbers before selecting an error-code table.
Important: The same LED count or code can represent a different fault on another model. Use only the table that specifically lists the equipment being tested.
1. Reference Contents
| Section | What It Provides |
|---|---|
| Error-code tables | Model-specific indoor and outdoor faults, including displayed codes and component descriptions. |
| LED pattern references | Operation, Timer, Economy, Filter and outdoor PCB flashing patterns. |
| Thermistor values | Temperature, resistance and voltage values for room, indoor heat exchanger, discharge, outdoor heat exchanger and outdoor-air thermistors. |
| Controller references | Wired controller, simple controller, group controller and network-convertor fault displays. |
| J-Series section | Normal operation displays, outdoor PCB LED layouts and J-Series fault indications. |
2. Model Families Covered
The reference includes a broad range of earlier product families. Examples include:
Wall-mounted and floor systems: AST, ASTA, ASTG, AWT and AWTZ series
Ducted systems: ART, ARTA, ARTC and ARTG series
Cassette systems: AUT, AUTA, AUTF and AUTG series
Under-ceiling systems: ABT, ABTA and ABTF series
Outdoor units: AOT, AOTA, AOTD, AOTG, AOTR and AOTZ series
Ducted systems: ART, ARTA, ARTC and ARTG series
Cassette systems: AUT, AUTA, AUTF and AUTG series
Under-ceiling systems: ABT, ABTA and ABTF series
Outdoor units: AOT, AOTA, AOTD, AOTG, AOTR and AOTZ series
The PDF table of contents provides the complete model-to-page index. Use the exact model designation, including suffix letters, to locate the correct table.
3. How to Use the Reference
- Record the complete model numbers from both the indoor and outdoor unit rating labels.
- Identify the display type - controller code, indoor-unit lamps, outdoor PCB LEDs or a combination of these.
- Use the table of contents to find the exact indoor/outdoor model combination.
- Count and record each flash sequence, including the lamp colour and the ON/OFF timing where shown.
- Cross-reference the fault description in the matching model section.
- Test the related circuit before replacing components.
Electrical safety: Isolate the equipment and allow capacitors to discharge before resistance, continuity or wiring checks. Live-voltage testing must only be completed by appropriately qualified personnel using approved procedures.
4. Recommended Diagnostic Workflow
| Step | Action | Key Check |
|---|---|---|
| 1 | Confirm the displayed code or LED pattern. | Record all lamps, counts and timing. |
| 2 | Verify the model-specific fault description. | Do not use a similar model as a substitute. |
| 3 | Inspect plugs, terminals, harnesses and PCB connections. | Look for loose connections, corrosion, moisture or damaged wiring. |
| 4 | Measure the related sensor or component. | Compare thermistor measurements at the actual sensor temperature. |
| 5 | Confirm the fault after corrective work. | Restart, run the system and check that the code does not return. |
5. Thermistor Reference Notes
- The thermistor tables begin near the front of the reference and list temperature against resistance and circuit voltage.
- Resistance changes significantly with temperature. Measure or estimate the sensor temperature before interpreting a reading.
- Disconnect the sensor from the PCB before resistance testing unless the applicable service procedure states otherwise.
- A sensor that is open, shorted or materially outside the table value should be checked together with its connector and harness.
Supporting document:
Error codes JM24082015.pdf - 100-page legacy error-code, LED and thermistor reference. Attach the PDF to this Freshdesk solution so technicians can open the complete model-specific tables.
Error codes JM24082015.pdf - 100-page legacy error-code, LED and thermistor reference. Attach the PDF to this Freshdesk solution so technicians can open the complete model-specific tables.
This article is an index and usage guide. The attached PDF remains the authoritative source for each model-specific code, LED pattern and reference value.