AC Tripping the Breaker in Lafayette

AC Tripping the Breaker in Lafayette

When an AC trips the breaker, the breaker is cutting power because something is pulling more current than it should. At startup the compressor and fan draw a hard surge, and if a capacitor is weak or a motor is straining, that surge climbs past the breaker's limit and it opens. Mid-cycle trips usually mean the compressor is laboring against high pressure. Either way it is a current problem with a specific cause, and the cause is what we measure for.

Lafayette's older hillside homes add a wrinkle. A lot of these mid-century custom houses still run their original electrical panels with limited capacity, and the AC circuit was sized tight from the start. That means a breaker here can trip on an amp draw that a newer panel would shrug off, and an aging breaker that has been heat-cycled for decades will weaken and trip below its own rating. We check the breaker and the panel along with the condenser.

Nearly every trip we get called for in Lafayette comes back to one part. It might be a capacitor, a contactor, a fan motor, or a worn breaker. Summers here run warm but not brutal, well short of the heat farther inland, so the compressor is not usually cooked from the weather. We read the amp draw to find which part it is before we quote a thing.

Common causes

Weak or undersized breaker. On older Lafayette panels, a breaker that has tripped and reset for years weakens and starts cutting out below its rating. We compare the breaker's amperage to the unit's nameplate, and if the breaker is fatigued or was undersized from the start, replacing it correctly is the fix. We will never upsize a breaker just to stop the nuisance. That defeats the protection it is there to provide.

Failed run capacitor. A capacitor that has drifted out of spec makes the compressor strain to start, and the amp draw climbs until the breaker opens. We meter the capacitance against the rating on the can and replace it if it reads low. This is the single most common trip we find, and it is a same-visit fix.

Pitted contactor. The contactor powers the outdoor unit, and when its contacts pit they arc and can spike current. We inspect the contacts and read the draw across them. A burnt contactor is a cheap part and a quick swap, and catching it early keeps it from frying the rest of the circuit.

Locked condenser fan motor. Hillside condensers tucked into landscape collect debris, and a fan bearing that seizes pulls locked-rotor amps until the breaker trips. We confirm the fan spins freely and read its running amps against the nameplate. A dragging motor gets replaced before high head pressure damages the compressor.

Shorted or grounded compressor. When compressor windings short to the case, the unit draws a near dead-short current the moment it starts. We isolate and ohm the windings to ground. A grounded compressor is a genuine failure, and on a 20-plus-year Lafayette system we lay out repair-versus-replace numbers on the estimate so you can decide.

Chafed wiring in tight access. Equipment crammed into a hillside lot or a tight crawl space often has wiring rubbing against framing or a cabinet edge. Once it wears through it shorts and trips instantly. We trace the disconnect, whip, and low-voltage runs for damage and repair the short.

How we diagnose it

• Read the actual amp draw with a clamp meter at the instant the unit trips, instead of guessing from symptoms.
• Check the breaker amperage and condition against the unit's nameplate, since older Lafayette panels run tight on the AC circuit.
• Test the run capacitor against its rating and inspect the contactor for pitting.
• Spin the condenser fan and read its running amps to catch a seizing motor.
• Ohm the compressor windings to ground before condemning the compressor, and inspect tight-access wiring runs for shorts.

$75 diagnostic, credited toward any repair over $200. You get a written quote before any work begins.

AC Tripping the Breaker in Lafayette: common questions

Nearby and related

AC Tripping the Breaker near Lafayette: Orinda · Moraga · Walnut Creek · Alamo .

This is usually a ac repair in Lafayette job. See our ac repair overview or the Lafayette service area.