One room would not cool. Another company said replace the compressor.
Two rooms cold, one room warm
A homeowner with a 7-year-old Daikin System 3 had a frustrating problem: two of the three rooms cooled perfectly, but one room would not cool at all. The aircon was running, air was coming out, but that one room stayed warm.
They called in a contractor for an assessment. The verdict: the compressor had "no strength" and needed a full replacement. For a System 3, that is a costly job, and the homeowner was planning to sell the house soon. Paying for a major compressor replacement right before selling made no financial sense.
So they did the smart thing. They looked for a second opinion.
Why "replace the compressor" did not add up
When our technicians Nazrul and Asad assessed the system, the compressor diagnosis did not fit the symptoms. Here is the logic:
If a compressor genuinely lacks strength, you would typically see weak cooling across all rooms, because the compressor serves the whole system. But in this case two rooms were cooling perfectly. That pattern points to a problem with the one indoor unit that was not cooling, not the shared outdoor compressor.
The team started with the most common and least expensive causes first, exactly the right order:
- Chemical wash on the affected indoor unit, in case buildup was blocking heat transfer
- Cleaning the compressor to rule out dirt-related performance loss
Even after this, that one room still would not cool. A lot of technicians would have stopped here and fallen back on the "replace the compressor" story. Our team kept troubleshooting.
The real culprit: a faulty fan coil PCB board
Through systematic troubleshooting, the team traced the fault to the fan coil PCB board in the problem unit. The PCB (printed circuit board) is the control brain of the indoor unit. When it fails, that single unit can stop cooling correctly even though the compressor, refrigerant, and everything else in the system are perfectly fine.
This is a textbook example of why diagnosis matters more than guessing. A faulty PCB on one indoor unit is a far smaller and cheaper fix than replacing the compressor for the entire system. The two problems share a symptom (a room not cooling) but live at completely opposite ends of the cost scale.
"They eventually discovered that the root cause was a faulty fan coil PCB board. I was genuinely impressed by their problem-solving mindset, and their commitment to finding a proper solution rather than jumping to expensive replacements."
A working aircon, without an unnecessary compressor bill
The room cooled properly again, the homeowner avoided a costly and unnecessary compressor replacement right before selling their house, and the actual fault was fixed at the source.
The takeaway for homeowners
If one room is not cooling but the others are fine, the problem is very unlikely to be your compressor. A compressor issue affects the whole system, not one room. Before agreeing to an expensive compressor replacement, get a second opinion that includes proper troubleshooting of the individual indoor unit, its PCB board, and its fan coil. The difference in cost can be enormous.
Want an honest second opinion?
If you have been told you need an expensive replacement, get a proper diagnosis first. Same-day appointments, transparent pricing, no upselling.