Cold Air Prevention Control - Software Malfunction After Defrost
This article summarises a service bulletin relating to a software malfunction affecting the cold air prevention control at the start of heating operation after defrost.
Issue Summary
Under normal operation, cold air prevention control reduces the indoor airflow when heating first starts so that cold air is not discharged into the room.
On affected units, the software malfunction can cause the indoor fan to run at the airflow setting selected by the remote controller immediately after defrost. The source bulletin states that there was no trouble information reported from the market at the time of issue.
Countermeasure Options
Market corrective action can be carried out in either of the following two ways:
- Replace the PCB with the countermeasure version.
- Rewrite the PCB software using the countermeasure software, rewrite procedure manual and rewriting connection cable drawing.
How to Identify Countermeasure PCB
The countermeasure PCB is identified by the final three-character code shown after the PCB model name on the model-name label.
| PCB Type | Before Countermeasure | After Countermeasure |
|---|---|---|
| K06AK PCB | A04 | A24 |
| K14UY PCB | A08 | A13 |
Applicable Models and Serial Ranges
| Model | Shipments | Serial Range | Applicable PCB | Parts No. |
|---|---|---|---|---|
| ARTG30LHTA | 11,754 | T000001 to T011754 | K06AK-100PHSE-C1 | 9710621987 |
| ARTG36LHTA | 17,485 | T000001 to T017485 | K06AK-100RHSE-C1 | 9710621994 |
| ARTG36LHTB | 665 | T000001 to T000655 | K06AK-110PHSE-C1 | 9710620997 |
| ARTG45LDTA | 1,877 | T000001 to T001877 | K14UY-1506HSE-C1 | 9710016134 |
| ARTG54LDTA | 1,566 | T000001 to T001566 | K14UY-1507HSE-C1 | 9710016141 |
| ARTG60LDTA | 2,562 | T000001 to T002562 | K14UY-1508HSE-C1 | 9710016158 |
| Total | 35,899 | |||
Service Guidance
- Confirm the unit model and serial number are within the applicable range above.
- If the symptom occurs after defrost, confirm whether the indoor fan immediately operates at the remote-controller set airflow instead of reduced cold-air-prevention airflow.
- Check the PCB model and suffix to determine whether the countermeasure PCB is already installed.
- If the original software version is present, corrective action can be completed by PCB replacement or approved software rewriting.
- Follow the applicable rewrite procedure and connection-cable instructions where software rewriting is used.
Service Bulletin Images
The original Freshdesk-hosted bulletin images are retained below for reference.
