Why Is My Air Conditioner Not Cooling?

Protect people before diagnosing equipment.

During extreme heat, move vulnerable people to a reliably cooled place. If you smell burning, see damaged wiring, hear arcing, or a breaker repeatedly trips, turn the system off without opening equipment and call qualified service.

Mode, set point, schedule, and fan settings can imitate a failure.

Set the mode to cooling, choose a target below the measured room temperature, and wait through any documented compressor delay. “Fan on” can circulate room-temperature air between cooling cycles, so use the manufacturer-recommended fan setting for the test.

A restricted return or filter changes the entire system.

Check the filter against the equipment instructions, keep returns and supply registers unobstructed, and compare airflow around the home. Do not operate without a required filter or reach inside a blower compartment.

Temperature split alone does not authorize invasive work.

Ice, oil residue, recurring breaker trips, a silent outdoor unit, or continued warm air after visible checks needs licensed HVAC diagnosis. Refrigerant handling and internal electrical testing are professional work.