Error after neighbour renovation: communication wire nicked in trunking
A Hougang HDB unit started flashing an error after nearby renovation works. The timing made the homeowner worry about a failed board, but the first check was whether the wiring path inside the trunking had been disturbed.
By Team Snowflake | Updated 28 Jul 2026
Case summary
Mitsubishi Electric Wall-mounted8 years oldHDBHougang, Singapore
- Concern
- The household worried the indoor board had failed because the error appeared suddenly.
- Found
- Communication wire insulation nicked inside shared trunking route
- Key check
- Opened the trunking route and checked continuity before quoting board work
- Result
- The unit started normally after the wiring route was repaired. The error cleared without board replacement, and the homeowner had a clear explanation tied to the renovation timing.
What we were told
The bedroom unit had worked normally before renovation noise started from the next room. After that, it powered on, flashed an error, and stopped cooling. Nothing had been serviced recently, so suspicion fell straight onto the electronics.
What we checked
The timing mattered more than the error label alone. A board can fail on its own, but a fault that begins right after drilling or trunking work makes the cable route worth checking first. We opened the trunking near the affected indoor unit and traced the low-voltage wiring before discussing board replacement.
The indoor unit powered up, so the main supply was present.
The error returned quickly after each reset attempt.
A section of communication wire showed damaged insulation inside the trunking route.
The board area was dry and showed no visible burn mark or water staining.
What we found
The communication wire had been nicked where the trunking route passed near recent work. The damage was small from the outside, but it was enough to interrupt the signal between units and trigger the error. Because the fault followed the disturbed route, replacing the board would not have fixed the problem. The useful clue was the timing: a sudden error after renovation should make the wiring path part of the first inspection. This is why the wall route matters as much as the unit display.
What fixed it
We isolated the damaged section, replaced the affected wiring run, and protected the route before closing the trunking again. The quote stayed focused on restoring the cable path, not replacing electronics that had not been proven faulty. We also advised the homeowner to photograph the trunking path before future drilling or fixture work near the aircon line, especially in older flats where several services can run close together.
Outcome
The unit started normally after the wiring route was repaired. The error cleared without board replacement, and the homeowner had a clear explanation tied to the renovation timing.
What this case teaches us
Post-renovation errors need the wiring route checked first
- A new error after drilling or trunking work is not automatically a failed board. The wiring route may have been disturbed even when the aircon unit itself was not touched.
- Hougang flats with older trunking routes can hide small wire damage behind covers. Opening the route is slower than guessing, but it prevents unnecessary board replacement.
- Tell the technician what changed around the wall. Renovation timing, drill points, and new trunking covers help narrow the first check.
Questions this case answers
Aircon showing an error right after renovation next door: is the board gone?
Can drilling near the aircon trunking cause a fault even if nobody touched the unit?
The error keeps coming back straight after every reset. What does that mean?
What should I do before drilling near an aircon in an older flat?
Ready to get started?
Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.