AC Keeps Tripping the Breaker

Do not keep resetting the breaker

A circuit breaker detects dangerous electrical current and cuts power. If your AC trips breaker switches repeatedly, flipping the switch back on over and over creates intense heat in the wiring and components.

Repeated breaker resets can turn a simple part replacement into major equipment damage. If the breaker shuts off immediately or trips every time the system starts, leave the switch off until you locate the trouble.

A failing capacitor can cause high current

A run capacitor gives the motors in your AC an electrical push to start and keeps them running smooth. When a capacitor weakens or fails, the motor cannot spin easily. It pulls heavy electrical current as it hums in place, which trips the breaker.

A dual run capacitor powers two motors from one can and has three terminals marked HERM for the compressor, FAN for the outdoor fan, and C for common. A single run capacitor uses two terminals. If the capacitor is bad, you must replace it with the correct ratings.

• µF or MFD rating must match the old part exactly.
• Voltage must be the same or higher, such as replacing a 370 V unit with a 440 V unit.
• The physical shape must fit your mounting bracket, whether round or oval.

Condenser fan motor failure

The condenser fan motor spins the fan on top of your outdoor unit to release heat. If the motor bearings fail or the internal windings short out, the motor draws too many amps and shuts down the breaker.

Before replacing the entire motor, check the capacitor. A fan that hums but will not spin is often a bad capacitor, not a bad motor. A capacitor costs less, so checking it first makes practical sense. When a motor does fail, match its horsepower, RPM, and voltage ratings exactly.

A compressor that struggles to start

The compressor pumps refrigerant through the system and draws the most power of any component. As a compressor ages, mechanical friction or high head pressure can make startup difficult. This high startup current often trips the circuit breaker.

Some systems use a hard start kit to help with this load. A hard start kit adds a start capacitor for a moment at startup, then drops out. Start capacitors show a microfarad range rather than a single number and are not the same as run capacitors. Most units start fine without one, so inspect the run capacitor before assuming the compressor needs extra assistance.

Burnt wires and worn contactors

Your thermostat sends a small 24 V signal from a transformer to the contactor coil. The coil pulls the contacts closed, and 240 V power flows to the compressor and fan. Over time, electrical arcing burns and pits these metal contacts.

Pitted or stuck contacts create electrical resistance and loud buzzing. In severe cases, high heat melts wire insulation and causes a direct electrical short against the metal cabinet. Inspect the contactor for pitting or burnt terminals, ensuring the breaker and outdoor disconnect are off first.

• Match the pole count, which is usually 1 or 2 poles.
• Check the coil voltage, which is 24 V on most residential systems.
• Ensure the full load amp rating is the same or higher than the old part.

Safe inspection steps for homeowners

If you want to look at the outdoor unit, work systematically and stay safe. Never rush when dealing with 240 V line voltage.

1. Turn off the AC breaker in your main electrical panel.
2. Pull the outdoor disconnect handle at the unit, then use a meter to test for power.
3. Remove the access panel and discharge the capacitor with an insulated tool.
4. Take a photo of every wire before removing or moving any connection.
5. Look for burnt contacts, swollen capacitors, or bare wires touching metal surfaces.