A breaker that trips when the AC turns on usually means the unit is drawing too much current as it starts. Common causes are a failing start capacitor or compressor, a dirty outdoor unit, a worn breaker, a loose connection, or a circuit or panel that is undersized. Reset it once. If it trips again, leave it off and call.
Common causes
A weak or failing capacitor, which helps the compressor start
A compressor that is struggling or failing
A dirty outdoor coil or a blocked fan, which makes the unit work harder
A worn breaker that trips below its rating
A loose or corroded connection at the breaker or the disconnect
A breaker or wire not sized correctly for the unit
A panel that is too small for the home’s total load
What you can safely do
Turn the thermostat off.
Reset the breaker once: push it fully to OFF, then ON.
Give the system a little time, then turn the thermostat back on.
If it trips again, leave the breaker off and the thermostat off.
Make sure nothing is blocking the outdoor unit.
Electrician or AC technician?
It can be either. Capacitor, compressor and coil problems are for an HVAC technician. Breaker, wiring and panel problems are for an electrician. If you are not sure, call us at (602) 999-2770. A real person answers, and we will tell you honestly on the phone which one you likely need. If it is ours, you will hear the price before anyone drives out.
Do not do this
Do not keep resetting the breaker, and do not swap in a larger breaker. Both can let wiring or the AC motor overheat.
A burning smell at the panel or the outdoor unit means stop and call. If you see smoke or fire, call 911.
Common questions
Is it safe to keep resetting the AC breaker?
No. Reset it once. Repeated resets can overheat wiring or damage the AC.
Can a bad breaker cause the AC to trip?
Yes. Breakers wear out, and a worn one can trip under a normal load. An electrician can test it.
Why do my lights also dim when the AC starts?
A brief dim is common as the motor starts. Strong or worsening dimming can point to a weak connection or an undersized panel.
Want it checked?
A real person answers any hour, and we tell you honestly whether it can wait.
