Safety first. If you smell burning or the breaker trips again right after a reset, turn the system off at the thermostat and the breaker and leave it off. That's an electrical fault.
Start at the thermostat
Check that it's on Cool, not Heat, Em Heat or Fan. Heat pumps are easy to bump into heat mode, and on the first cool morning of the year that's often all it is. Set the fan to Auto: with the fan on On, the blower keeps pushing air between cooling cycles and it feels warm.
Then walk to the outdoor unit
- Silent: no power reaching it. Check the outdoor breaker in the panel and the disconnect box next to the unit (some have a pull-out block that must be seated).
- Humming, fan not turning: classic failed capacitor or a seized fan motor. Turn it off. A humming compressor that can't start overheats.
- Running, but the air inside is warm: low refrigerant, a very dirty outdoor coil, or a compressor that isn't pumping.
- Clicking on and off: a contactor, a control problem, or the compressor tripping on overload.
Heat pumps: the reversing valve
If you have a heat pump and it blows warm in cool mode (or cold in heat mode), the reversing valve or its solenoid may be stuck, or the thermostat wiring is wrong after a thermostat change. That's a technician job.
When to call
If the thermostat and breakers are fine and it's still warm after 20–30 minutes, call. Tell us what you heard at the outdoor unit: it helps us bring the right parts. You get a flat written price before any work.
AC Repair across Miami-Dade, Broward and Palm Beach. Written price before any work.