A breaker that trips when the air conditioner starts is doing its job. Resetting it until the AC finally stays on is not troubleshooting; it is repeatedly energizing a fault.
Reset it once, then stop
Turn the thermostat off. Move the labeled HVAC breaker fully to Off and then back to On one time. If it opens again, leave it off. The cause may be inside the air conditioner, in the branch circuit or at the breaker itself, and live testing is required to separate those possibilities.
If you smell burned insulation, see smoke or hear arcing, keep clear of the equipment and call for urgent help. Water near electrical components is another reason not to reset anything.
What can create the extra current
A weak capacitor can leave a motor struggling to start. A failing compressor or fan motor may draw excessive current. Damaged wiring, loose terminals and a worn breaker can produce heat and unstable operation. During severe Tucson heat, a dirty outdoor coil can also raise the load on an already weak system.
None of those problems is fixed by installing a larger breaker. Breaker and wire sizes are selected for the equipment. Increasing protection without correcting the fault can create a serious hazard.
Details worth noting before the technician arrives
Was the trip immediate or did the AC run for several minutes? Did the indoor blower stay on? Was there humming at the outdoor unit? Did the problem begin after a storm or outage? These observations shorten the path to diagnosis without requiring you to remove a cover.
What the repair should accomplish
The goal is not merely to make the breaker remain on. The technician should identify why the current exceeded a safe level and verify normal startup and operation after repair.
Call 520-303-3220 or use our emergency HVAC page. Related electrical work is available through Sonoran electrical repair.