ARTG24LMLC - Wired Remote Controller Not Displaying Due to Indoor Unit Miswiring

This article summarises the quality assurance investigation into an ARTG24LMLC unit where the wired remote controller did not display during installation due to incorrect indoor unit wiring.

Issue Summary
  • Product: ARTG24LMLC
  • Serial / reference: R000794
  • Reported symptom: Wired remote controller did not display during installation
  • Cause found on site: Incorrect wiring at the indoor unit

Problem Description

During installation, the wired remote controller did not display. The attending technician inspected the indoor unit and found that the wiring was incorrect.

Factory Investigation

1. Manufacturing Record Review

The factory checked the manufacturing records and confirmed there was no repair history recorded for the affected product.

2. Previous Occurrence and Earlier Countermeasure

The factory confirmed that the same type of wiring problem had occurred previously.

  • A jig tool and work process instruction had previously been introduced to prevent incorrect wiring.
  • The original jig was difficult to use.
  • As a result, the jig was not consistently used by factory workers.
  • The factory also used a control checker to verify the unit.
  • The checker required the worker to confirm both the monitor result and the LED result.
  • Because both checks relied on operator confirmation, there was a possibility that the LED result could be missed.

From 10 July 2014, the work process instruction was revised so the confirmation sequence was clearly defined:

  1. Confirm the monitor result first.
  2. Confirm the LED result second.

The affected ARTG24LMLC was manufactured before this revised process was implemented.

Likely Cause

Cause TypeFactory Assessment
Generation causeThe factory considered it likely that the worker did not use the original jig tool, allowing the wiring error to occur.
Inspection escape causeThe factory control checker required separate monitor and LED confirmation, creating the possibility that the LED result was missed during inspection.

Corrective Actions - Preventing Miswiring

  1. New jig tool introduced. The new jig was designed so incorrect wiring could be identified by placing the jig directly onto the terminal.
  2. Work process instruction updated. The usage method for the new jig was formally added to the work process instruction from 4 December 2014.
  3. Worker training added. When the responsible worker changes, the production leader is required to train the new worker using the revised work process instruction.
Jig function: If the wiring direction is incorrect, the jig cannot be correctly fitted. This provides a physical indication of miswiring before the unit proceeds further through production.

Corrective Actions - Preventing Inspection Escape

Interim Measure

The work process instruction was clarified so the inspection sequence was performed in a fixed order:

  1. Confirm the monitor result.
  2. Confirm the LED result.

Permanent Measure

From 23 January 2015, confirmation of the wired cable connection was added to the heat run check software.

Key factory improvement: The permanent software check was introduced so wired cable miswiring could be detected as part of the heat run verification process, reducing reliance on visual operator confirmation alone.

Action for Existing Product

  • Already installed product: Rectify on a case-by-case basis if the problem occurs.
  • Stock product: No blanket corrective action was specified in the original report, as the factory considered the issue unlikely to occur frequently.
  • Current production: Corrective measures had already been implemented.

Service Guidance

If a wired remote controller does not display on an ARTG24LMLC or similar system:

  1. Confirm power supply to the indoor unit.
  2. Inspect the wired remote controller cable termination at the indoor unit.
  3. Check the terminal positions and wiring direction against the applicable wiring diagram.
  4. Look for reversed, displaced or incorrectly terminated conductors.
  5. Correct the wiring if required.
  6. Restore power and confirm the wired remote controller display operates normally.
  7. Confirm normal indoor unit operation after the wiring correction.
Reference: Original quality assurance report referenced appendices covering manufacturing history, updated jig/work instruction, and the revised inspection process.