Quality / Service Technical Reference
Refrigerant Noise During Cooling - ASTG12LVCC
Suspected heat exchanger piping insertion / solder intrusion issue
A quality assurance problem report identified a case of abnormal refrigerant noise during cooling operation on an ASTG12LVCC indoor unit.
Affected Product
| Model | ASTG12LVCC |
| Serial number | Unknown |
| Reported symptom | Refrigerant noise during cooling operation |
Analysis Result
The reported ASTG12LVCC unit could not be analysed because the sample unit was not available for investigation.
However, a similar issue had previously occurred on an ASTG09LVCC. The heat exchanger used on the ASTG09LVCC was identified as being the same heat exchanger as the ASTG12LVCC.
Important: Because the affected ASTG12LVCC sample was not available, the actual cause of this case was not directly confirmed.
Suspected Cause
The suspected cause was considered to be the same as the earlier issue referenced as GS14-031.
- Pipe components may have been insufficiently inserted before welding/brazing.
- Welding was then carried out with the pipe not fully inserted.
- This condition could allow solder to flow into the refrigerant pipe.
- The internal solder intrusion may then disturb refrigerant flow and create abnormal refrigerant noise during operation.
Finding: The solder-intrusion mechanism was a suspected cause only for this ASTG12LVCC case because the returned sample was not available for confirmation.
Factory Corrective Action
The factory revised and formalised the piping insertion method to reduce the risk of insufficient pipe insertion before welding/brazing.
- A defined piping insertion method was prescribed.
- The revised manufacturing method was implemented for current production.
Product Action
| Product Status | Action |
|---|---|
| Already installed | Address on a case-by-case basis if the problem occurs. |
| Stock product | No action specified. |
| Current manufacture | Corrective manufacturing action implemented. |
Service Guidance
- If abnormal refrigerant noise is reported on an ASTG12LVCC during cooling, confirm the operating condition and whether the noise is consistently reproducible.
- Check for other causes of refrigerant noise before assuming a heat exchanger manufacturing issue.
- Where the fault appears consistent with this historical issue, record the full model and serial number and escalate for technical review.
- If a heat exchanger is replaced, retain the affected component where practical for analysis.
Information to Collect if the Issue Reoccurs
| Item | Details Required |
|---|---|
| Unit identification | Full model and serial number |
| Operating condition | Cooling mode, set temperature and room temperature |
| Noise description | When the noise occurs and whether it is continuous or intermittent |
| Evidence | Video or audio recording of the noise where possible |
| Component retention | Retain the heat exchanger if replaced and practical to do so |
Important: The original ASTG12LVCC report did not establish a confirmed root cause. The suspected cause was based on a previous ASTG09LVCC case using the same heat exchanger.