Aircond Keeps Tripping the Circuit Breaker? 5 Likely Causes

The capacitor is a small cylinder that helps the compressor start by buffering the initial current surge. When it wears out (especially in units 5+ years old), it can't handle the startup load, and the compressor draws excessive current, instantly tripping the MCB.

Signs: Tripping happens within 1–2 seconds of startup. Unit sometimes starts, then trips on next attempt. The capacitor may look slightly bloated or burnt-smelling.

Low refrigerant forces the compressor to work much harder to achieve cooling. This excessive work draws far more current than normal, overheating the motor windings. The MCB sees the overcurrent and trips to prevent damage.

Signs: Unit gradually loses cooling ability over weeks/months. Poor cooling, ice on the indoor unit or copper pipes. Unit trips when running for more than a few minutes under load.

If the outdoor condenser coil is clogged with dirt, leaves, or debris, airflow is restricted. The compressor overheats trying to reject heat, drawing excessive current and triggering the MCB.

Signs: Outdoor unit visibly clogged with debris or grime. Unit cools poorly or not at all. Problem is worse on hot days when the compressor works hardest.

Damaged insulation, rodent damage to wires, water ingress at the isolator box, or a failing compressor motor can all cause a short circuit. This is the most dangerous cause because it creates a fire risk.

Signs: Trips immediately on startup, every single time. You may smell burnt plastic or rubber near the outdoor unit or electrical isolator. Tripping happens even when MCB is brand new.

If the aircond shares a circuit with other high-draw appliances (washing machine, water heater, oven, kettle), the combined load exceeds the MCB's rating. When the aircond and another appliance run simultaneously, the circuit trips.

Signs: MCB trips only when the aircond is on AND another appliance is running (like the oven or washing machine). Never trips if the aircond runs alone.