Error code the day renovation finished: signal wire nicked
The unit was one year old and worked fine before the renovation. The error appeared the moment the contractor finished, and the renovation company blamed the aircon. The timing pointed somewhere else.
By Team Snowflake | Reviewed 11 Mar 2026
Case summary
Daikin Wall-mounted1 years oldHDBTengah, Singapore
- Concern
- Thought the renovation work had permanently damaged the aircon unit.
- Found
- Signal wire between the indoor and outdoor unit had been nicked during renovation and rejoined with the wires swapped
- Key check
- Traced the signal wire from the indoor unit to the outdoor unit and checked the wire order against the wiring diagram
- Result
- The error cleared on the first power-on after the correction. The unit went back to normal cooling, and no parts were replaced on the one-year-old system.
What we were told
The unit worked fine before the renovation. After hacking and retiling in the living room, it started flashing an error and would not turn on. The renovation contractor said the aircon must have had a fault all along.
What we checked
An error that appears right after building work points to something the work disturbed. We traced the cable that carries signals between the two units through the renovation zone before testing any parts.
The error code pointed to a signal fault between the indoor and outdoor units. It was not a compressor, sensor, or power code.
The signal cable ran through the wall section that had been hacked. A taped join was visible inside the damaged area.
The wire order at the join did not match the maker's colour-code diagram. The data and ground wires were swapped.
Both control boards responded normally once the join was corrected. The units linked up on the first power-on, so no board was damaged.
A continuity test along the full cable run showed no other breaks beyond the visible join.
What we found
During hacking, a drill or chisel cut through the signal cable that links the indoor and outdoor units. Someone on site, likely a renovation worker and not an aircon technician, stripped the damaged ends and joined them back. The wires went back in the wrong order. Each wire in the cable carries a set role: power, data, and ground. With two wires swapped, each board was sending on the wire the other expected to receive. The units could not link up, so the error repeated on every start. Both boards were undamaged. They were working correctly, just talking on the wrong lines.
What fixed it
We opened the join, matched each wire to the maker's colour-code diagram, and rejoined them in the correct order with proper insulated connectors. We then powered the units up, outdoor first and then indoor, and saw a clean link with no error codes. We ran a full cooling cycle and checked the temperature gap and power use. We also suggested the client ask the renovation contractor to cover the service call cost, since the damage happened during their work.
Outcome
The error cleared on the first power-on after the correction. The unit went back to normal cooling, and no parts were replaced on the one-year-old system.
What this case teaches us
When an error follows renovation, suspect the wiring first
- An error that appears the day work finishes usually traces to what the work disturbed, not to the aircon itself.
- A communication error means the two units cannot talk to each other. That is often a damaged or miswired cable, not a failed board.
- Keep the wall section where cables run noted before hacking starts. A nicked signal cable is cheap to rejoin once it is found.
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