Error Code the Day Renovation Finished: Signal Wire Nicked

Error codes appearing on a system that ran without complaint for years, starting some weeks after renovation work in the property. The work did not involve the aircon. Both units otherwise operate normally between the faults.

A system that worked, then had building work happen around it, then began faulting is describing a sequence worth taking seriously. That holds even when the trades involved never touched the equipment. Signal wiring runs through the same walls, ceilings and trunking that other work passes through, and a blade or a fixing that nicks insulation leaves a cable which still works. The gap between the work and the fault is what hides it. The useful question is what happened in the property, not what is wrong with the machine.

A nick in insulation does not stop a wire conducting. It exposes a small area of conductor, and from that point moisture, movement and temperature cycling do the rest over weeks or months. Eventually the signal between the units becomes unreliable and codes begin appearing. The damage was done on a specific day and the symptom arrives on a different one, which is exactly why the connection is missed.

Locating the damaged section and repairing or replacing it is the work, along with protecting the route where other trades are likely to pass again. What generalises is the question rather than the repair. Before investigating equipment that ran for years without trouble, find out what has been done to the property recently. The answer frequently ends the diagnosis before any panel comes off the wall.