Does a flashing light always mean the PCB is faulty?

No. Flashing lights can come from communication issues, wiring faults, or other causes. The board should not be the first assumption without checks.

Can renovation work affect aircon wiring?

Yes. Work near trunking or wall routes can disturb connections or cable paths. The timeline matters when the error begins after nearby work.

What should I share for a second opinion?

Share when the flashing started and whether any nearby work happened before it. That timeline helps us choose the first checks.

Flashing Light After Renovation, Not PCB Replacement

A flashing light started soon after work near the aircon trunking. The first advice was a board change, but the timeline pointed to a connection issue first.

Case Details

LocationSerangoon, Singapore

BrandMitsubishi Electric

Unit age6 yrs

ComplaintWork was done near the wall trunking. After that, the unit started flashing and cooling became unstable. A board change was suggested.

CauseDisturbed signal wire connection near the terminal path

The Assessment

When a fault starts after nearby work, the timeline matters. We checked connection points and the signal path before moving to a board change.

Flashing light started after nearby renovation work
The fault was not a random long-term pattern
Connection issue was found in the signal path
The symptom did not prove a failed board first

The Diagnosis

The signal path between indoor and outdoor sides was disturbed. A wire connection in that path was not secure. This caused flashing errors and unstable cooling. The symptom looked like a board fault, but the connection path matched the timeline better.

Correct the signal-wire connection, secure the terminal path, and retest cooling before discussing any board replacement.

The Outcome

After the signal path was corrected and secured, the flashing light stopped and cooling returned to normal. Board replacement was not needed.

Timeline

Before workUnit operated normally

Renovation periodNearby trunking area was worked on

After workFlashing light and unstable cooling started

Snowflake visitCommunication connection fault found

After correctionFlashing stopped and cooling normalized

What This Means for You

A fresh timeline change often points to disturbed connections before major part failure.

Flashing light started after renovation or trunking work
Board replacement was suggested without checking recent work areas
Cooling became unstable at the same time the flashing started

Ask for the communication-wire path and connection points to be checked first.