In a Miami house the air conditioner runs most of the year, and on a July afternoon it may barely stop. So when its breaker trips, you notice within the hour. A tripped AC breaker can come from the air conditioner itself, from the circuit that feeds it, or from the breaker. Some of those are an HVAC technician's job and some are an electrician's, and knowing which is which saves a wasted visit. This guide covers central systems with an outdoor condenser and an indoor air handler, which is what most South Florida homes have.
First, which breaker tripped?
A central system usually has at least two circuits, each with its own double breaker in the panel:
- The condenser (outdoor unit). It holds the compressor, the outdoor fan motor, a capacitor and a contactor. This is the biggest load in most homes, and the breaker that trips most often.
- The air handler (indoor unit). In a closet, attic or garage. It holds the blower motor and, in many Miami homes, electric heat strips for the few cold mornings a year.
- The outdoor disconnect. A small box on the wall next to the condenser. It lets a technician shut the unit off where they are working. Some contain fuses or a breaker of their own, so the unit can lose power there even when the panel looks fine.
Note which one tripped, and when: at startup, after running a while, only on the hottest afternoons, or the first time the heat came on. That detail tells the technician more than anything else.
Causes in the outdoor unit
- A failing capacitor. The capacitor helps the compressor and fan motor start. When it weakens, the compressor struggles, draws heavy starting current for longer, and can trip the breaker. You may hear the unit hum or click without the fan turning. Lights that dim deeply when the AC starts are a related sign; our guide to lights that flicker when the AC turns on covers that symptom.
- A compressor that is wearing out. A compressor with a winding failing, or one shorting to its housing, will trip the breaker immediately or within seconds. This is the expensive repair, and it needs an HVAC diagnosis.
- A worn contactor or fan motor. Pitted contacts, a seized fan motor, or a fan that has stopped so the unit overheats.
- Hot-afternoon trips. A dirty outdoor coil, a refrigerant problem or a struggling fan makes the compressor work harder, and it draws more current as the day heats up. A breaker that only trips at three in the afternoon in August often points here.
- Salt air and water. Near Biscayne Bay and on Miami Beach, terminals, contactors and the disconnect box corrode faster. Water getting into the disconnect, or a damaged flexible conduit between the disconnect and the unit (lawn trimmers are a common cause), can create a fault. See salt air corrosion.
Causes in the air handler
- Heat strips on the first cold morning. Electric heat that has not run since last winter is a large load, and a failing strip or its wiring can trip the breaker the first time the thermostat calls for heat.
- The blower motor. A motor or its capacitor failing, or a blower that is clogged and straining.
- Condensate water. A clogged drain normally just shuts the system off through its float switch, which does not trip the breaker. But a pan that overflows onto wiring, or water dripping into the air handler's electrical compartment, can.
Causes on the electrical side
- The breaker itself. AC breakers carry a heavy load for thousands of hours. One that has worn, overheated or loosened on the panel bus can trip below its rating.
- A loose or burned connection at the breaker, in the disconnect, or at the unit. Loose connections heat up under the AC's steady load.
- A breaker that does not match the unit. The unit's label lists the maximum breaker or fuse size and the minimum circuit size. If a breaker was replaced with the wrong size or type, or a new unit was put on an old circuit, the two may not match.
- GFCI protection on the AC circuit. Florida amended the national outdoor GFCI rule so that GFCI protection is not required for listed and labeled HVAC equipment (FBC-Residential E3408.1, amending NEC 210.8(F)). If a GFCI breaker was installed on your AC anyway and trips, ask an electrician to look at it. Do not swap breakers yourself.
What you can safely do
- Turn the thermostat off first, then reset the breaker once, pushing it fully to OFF and back to ON. Give it several minutes before turning the thermostat back on, so the compressor is not trying to start against pressure. Our guide to breakers that trip again on reset explains why one reset is the limit.
- If it trips again, leave it off and call. Running a unit that keeps tripping can damage the compressor and wears out the breaker.
- Look and listen at the outdoor unit, without opening it: humming with no fan, repeated clicking, a burning smell, or debris packed against the coil.
- Check the air handler's drain area for standing water or a wet floor.
- Do not open the disconnect, the unit's panels or the electrical panel cover, and do not hose down the unit's electrical compartment.
Who fixes which part
The parts inside the condenser and air handler are an HVAC technician's work: the capacitor, contactor, compressor, fan and blower motors, refrigerant, heat strips, float switch and drain. The circuit is an electrician's work: the breaker, the wire from the panel, the disconnect box, the flexible conduit to the unit, and the connections at the panel. If you are not sure where the fault is, our guide to appliance tech, HVAC tech or electrician sets out how to decide. When the HVAC technician finds the unit healthy and the breaker still trips, that is the point to call us.
What we check
We measure the current the unit draws at startup and while running, compare it to the label, and check the breaker, the disconnect and every connection between the panel and the unit for heat, corrosion and looseness. We confirm the breaker and wire size match the equipment. If the circuit is fine, we tell you so and which part of the unit to have looked at. Our circuit breaker repair page explains what we do with breakers that will not hold, and surge protection covers protecting the system from storm surges.
Questions people ask
Can I put in a bigger breaker so it stops tripping?
No. The breaker protects the wire and the unit. A larger breaker than the unit's label allows lets an overloaded or shorted circuit overheat instead of shutting off.
Why does it trip only on the hottest days?
The compressor works hardest and draws the most current when it is hottest outside. A unit with a dirty coil, a weak capacitor or a refrigerant problem crosses the line on those days first. That is usually an HVAC service call.
It started tripping after a storm. Why?
Water in the disconnect or the unit, or a surge that damaged a component. Leave it off and see our post-storm checklist before running it again.
Need it looked at?
KRW Electric (EC13012832) troubleshoots and repairs air conditioning circuits that keep tripping in Pinecrest, Coconut Grove, South Miami and Miami Beach, with same-day service when scheduling permits. Call (305) 359-7312 and tell us what you are seeing. We will ask a few questions, tell you whether it sounds urgent, and give you the earliest time we have. Our before you call checklist covers what to have ready, and what happens on a repair visit explains the rest.
Reviewed by Kyle White, KRW Electric Company LLC — licensed electrical contractor EC13012832.
