The Customer's Situation
Mr. Kevin Tan had been dealing with an annoying problem for two weeks. His master bedroom Daikin 1.5HP inverter aircond would run perfectly for about 25-30 minutes, then the MCB in his DB board would trip. He'd reset it, turn the aircond back on, and the cycle would repeat.
Kevin lives in a mid-floor unit at i-Zen Kiara in Mont Kiara. The condo was about 8 years old, but Kevin had done a renovation 2 years ago that included relocating the master bedroom aircond to a different wall. This detail would turn out to be crucial.
He'd already called another aircond company who told him the compressor was faulty and quoted RM1,800 for a replacement. Kevin wasn't convinced — the aircond was only 3 years old and a Daikin at that. He WhatsApped us for a second opinion.
Reported Issues
- MCB trips consistently after 25-30 minutes of cooling operation
- Fan mode works fine without tripping
- Aircond cools normally during the 25-30 minutes before tripping
- No unusual noises or smells
- Previous technician diagnosed compressor failure
Our Diagnosis
Our senior technician Hafiz arrived and started with the basics. He put a clamp meter on the aircond circuit — the running amperage was normal at 6.2A for a 1.5HP inverter unit. Compressor sounded fine. Gas pressure was within spec. The outdoor unit wasn't clogged.
Then Hafiz noticed something: the MCB was rated at 16A, which should be fine for a 1.5HP unit. But when he checked the wire gauge running from the DB board to the aircond point, he found the issue. The wire was only 1.5mm² — undersized for a dedicated aircond circuit, which should use at least 2.5mm².
Here's what was happening: during the renovation, the contractor had relocated the aircond point and used 1.5mm² wire (likely because that's what was available, or to save cost). The thinner wire had higher resistance, which caused it to heat up under the sustained load of the compressor. After 25-30 minutes, the accumulated heat in the wire triggered the MCB's thermal protection.
The compressor was perfectly fine — the previous technician's diagnosis was wrong.
The Repair
Work Completed
- Identified root cause: undersized 1.5mm² wiring on aircond circuit (should be 2.5mm²)
- Replaced entire wire run from DB board to aircond point with proper 2.5mm² cable
- Checked and tightened all connections at both ends
- Verified MCB rating appropriate for the circuit (16A — correct for 2.5mm² wire and 1.5HP load)
- Ran aircond for 2 hours continuous to confirm no more tripping
- Checked amperage draw throughout — steady at 5.8-6.5A, well within limits
Why This Matters
This case highlights a common problem with renovation work in Malaysian condos. Electrical work for aircond relocation should always use the correct wire gauge, but budget contractors sometimes cut corners. The 1.5mm² wire Kevin had is rated for general lighting and power socket circuits — not for sustained high-draw appliances like airconds.
When the MCB trips and the unit also makes unusual sounds, it often indicates compressor problems that need immediate attention. Ignoring these combined symptoms can lead to complete compressor failure.
The danger goes beyond just MCB tripping. Undersized wiring that heats up repeatedly can damage the wire insulation over time, eventually leading to short circuits or even electrical fires. Kevin was lucky his MCB was working correctly and catching the problem.
If your aircond keeps tripping the MCB, don't immediately assume the worst. Get a proper diagnosis that checks everything — including the wiring, not just the aircond unit itself.
Cost Breakdown
- Diagnosis fee: RM80 (waived as part of repair)
- 2.5mm² cable (15m run): RM120
- Labour (rewiring + testing): RM360
- Total: RM480
Compare that to the RM1,800 compressor replacement that Kevin was quoted by the other company. Proper diagnosis saved him RM1,320 and preserved a perfectly good Daikin compressor.
Customer Feedback
"I'm so glad I got a second opinion. The first company wanted to replace my compressor for RM1,800 when the real problem was just bad wiring from my renovation. Hafiz found the issue in 20 minutes. Aircond has been running perfectly since the rewiring — no more tripping at all."
— Mr. Kevin Tan, i-Zen Kiara, Mont Kiara
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