AC Keeps Tripping the Breaker

Short answer: If your AC trips the breaker, reset it once with the thermostat off. If it trips again, leave it off. Repeat trips mean something is drawing too much current or shorting, usually the compressor, the fan motor, the capacitor or burned wiring at the contactor. A warm breaker, a burning smell or a melted disconnect means call now. A breaker that trips is the system telling you to stop. Resetting it all afternoon is how motors and compressors finish themselves off. One trip can be a weak breaker or a hard start on a hot afternoon. A second trip means something is pulling too much current or shorting. The usual parts are a compressor that is mechanically tight, a fan motor that is seizing, a shorted capacitor, or wiring that has cooked at the contactor. Do not keep resetting it. If the breaker is warm, leaves a burn smell, or trips the moment you turn cooling on, leave it off and call. That is also true if the disconnect outside is melted. Those are not filter problems. In side yards in Southern Highlands, Anthem, and Mountains Edge, the electrical whip and capacitor live in full sun. We see swollen capacitors and pitted contactors constantly. Those are repairs. A compressor that is grounded is not, and we will show you the reading instead of asking you to trust a speech. If another company condemned the system because “it keeps tripping,” ask what the amp draw was and whether the capacitor was tested. Tripping is a symptom. It is not a diagnosis.

When it trips tells you a lot

Notice when the breaker goes, because the timing narrows down the cause before anyone opens a panel:

• Trips the instant cooling is called for. That points to a dead short: a shorted compressor winding, a shorted capacitor, or wiring touching metal. Leave it off.
• Trips a few seconds after the outdoor unit tries to start. A compressor that can't get turning draws locked-rotor current until the breaker gives up. A failed start capacitor or run capacitor is a common reason, and a mechanically tight compressor is the expensive one.
• Runs for a while, then trips in the heat of the afternoon. Current climbs as the system works harder. A matted condenser coil, a failing fan motor or low airflow can push amp draw up until a weak or undersized breaker lets go.
• Trips the indoor breaker, not the outdoor one. Look at the air handler or furnace side: the blower motor, its capacitor, or electric heat strips if the system has them.

What we measure

A tripping breaker gets a few readings:

1. Amp draw on the compressor and fan motor, compared with the nameplate ratings.
2. Capacitor values against the rating printed on the part. A swollen or leaking capacitor is usually obvious, but a weak one can look normal.
3. Compressor windings to ground. A grounded compressor is the reading that changes the conversation from repair to replace.
4. Contactor and wiring. Pitted contacts and heat-damaged lugs at the contactor and the disconnect are common in Las Vegas side yards where the electrical sits in direct sun.
5. The breaker itself. Breakers wear out too. If the equipment draws normal current and the breaker still trips, the breaker may be the failed part.

You'll see the numbers. If the fix is a capacitor or a contactor, that's a repair. If the compressor is grounded, we explain what that means for repair versus replacement. See repair or replace a 20-year-old AC.

What not to do

• Don't hold the breaker on or tape it. It trips to protect the wiring.
• Don't swap in a bigger breaker. Breaker size is matched to the wire and the equipment's rating, and a bigger one takes away that protection.
• Don't open the outdoor panel. Capacitors can hold a charge after the power is off.

If you smell hot plastic or something electrical, turn the system off at the thermostat, leave the breaker off, and schedule a visit. If the outdoor unit hums but won't start without tripping anything, see AC outdoor unit not running. For a capacitor that's already failed, see AC capacitor failure. To tell a failed capacitor or hard-start kit from a compressor problem, see capacitor, hard start, or compressor.

Is it safe to reset the breaker once?

Once, if there is no burn smell and the breaker is not hot. If it trips again, leave it off. Repeated resets are how a failing motor becomes a more expensive failure.

Can a bad capacitor trip the breaker?

Yes. A capacitor helps the compressor and fan motor start. When it fails, the motor can stall and draw locked-rotor current until the breaker trips. It's one of the most common causes we find, and it's a repair. We handle this across the valley, including Silverado Ranch.