What to check first
Confirm the thermostat is calling for cooling.
Set the thermostat to COOL, set the fan to AUTO, and lower the setpoint a few degrees below the room temperature. Give the system several minutes to respond.
Look at the filter and the return airflow.
A heavily loaded filter can restrict airflow and contribute to poor cooling or a frozen coil. Replace it with the correct size if it is visibly dirty.
Check the outdoor unit from a safe distance.
Make sure leaves, grass, and stored items are not blocking the condenser. Do not reach into the unit or remove panels while power is on.
Do not keep resetting a tripped breaker.
A breaker that trips again can point to an electrical or mechanical problem. Repeated resets can make the problem harder to diagnose and less safe.
If the refrigerant line or indoor coil is iced, stop cooling.
Turn cooling off and let the system thaw. You can run the fan if it still operates normally, but do not chip ice off the equipment. Ice usually means a problem worth diagnosing.