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Your AC switches on, runs for a few seconds or minutes, and then the MCB trips and the power goes off. It's frustrating — but it's also a safety device doing its job. The MCB is telling you that something is drawing too much current or leaking to earth.
Safety first
If you notice a burning smell, scorch marks on the socket or switch, or sparking, switch off the AC at the MCB and don't use it until it has been inspected.
Common causes of AC tripping
1. Weak or failed capacitor
The capacitor helps the compressor and fan motor start. When it weakens, the compressor struggles and draws heavy current, tripping the MCB or overload. This is one of the most common and inexpensive causes.
2. Compressor problems
A compressor with a shorted winding or one that is mechanically stuck draws very high current and trips the breaker immediately. A technician tests the windings and insulation to confirm this.
3. Loose or burnt connections
Loose terminals heat up, especially under summer loads. Burnt wires at the socket, indoor unit or outdoor contactor can cause tripping and are a fire risk.
4. Undersized MCB, wiring or socket
A 1.5 or 2 ton AC needs a suitably rated MCB, wire size and socket. Plugging a large AC into a light-duty socket or an undersized circuit causes nuisance tripping and overheating.
5. Earth leakage from water or damaged wiring
If your home has an RCCB/ELCB, water in the outdoor unit's electrical box, a damaged interconnecting cable or a leaking component can trip it — more common during monsoon rains.
6. Dirty coils and overheating
A choked outdoor coil makes the compressor run hot and draw more current, particularly on very hot afternoons.
7. Low or fluctuating voltage
Low voltage increases current draw and makes starting harder. Frequent fluctuations also stress the PCB on inverter ACs.
| When the MCB trips | Likely cause |
|---|---|
| Immediately when switched on | Short circuit, shorted compressor or wiring fault |
| When the compressor starts | Capacitor, compressor or undersized MCB |
| After running for a while | Overheating, loose connection or dirty coils |
| During or after rain (RCCB) | Water in outdoor unit or damaged cable |
| Stabiliser cuts off | Voltage outside range or undersized stabiliser |
What you can safely check
- Note exactly when it trips — at switch-on, at compressor start, or after some time.
- Check whether the socket, plug or switch looks scorched or feels hot (with power off).
- See if other heavy appliances share the same circuit.
- Check whether the outdoor unit is wet or its cover is damaged.
Anything inside the AC or the distribution board should be left to a trained technician or electrician.
Paras Refrigeration provides AC repair across Bhubaneswar, Cuttack, Puri and Khordha. If your AC stopped suddenly in peak summer, our emergency breakdown guide explains what to do while you wait.
Frequently asked questions
Paras Refrigeration Service Team
AC service technicians, Bhubaneswar · Last reviewed 7 Oct 2026
Written by the Paras Refrigeration service team from day-to-day experience repairing, installing and maintaining residential and commercial AC systems across Bhubaneswar, Cuttack, Puri and Khordha.
- #AC repair
- #MCB tripping
- #Electrical
- #Troubleshooting
