Why Is My AC Running but Not Cooling?

If the air conditioner runs but the house isn't getting cooler, work through the simple possibilities before assuming a major failure.

Check the thermostat

Make sure it's set to Cool, with the target temperature below the current room temperature. If the thermostat runs on batteries and the display is weak or acting strangely, check the batteries.

Check the filter

A heavily loaded filter restricts airflow. Inspect the filter and replace or clean it according to the filter and HVAC manufacturer's directions.

Check the vents

Walk through the house and make sure supply vents aren't closed or blocked by furniture, rugs, or other objects.

Look at the outdoor unit

From outside the cabinet, check whether leaves, vegetation, or debris are packed around the equipment. Don't open panels or reach in.

What if the air coming out isn't cold?

Then the problem probably goes beyond settings and airflow. Possible causes involve coils, controls, refrigerant conditions, electrical components, compressor operation, or other internal equipment. None of these are good guess-and-replace DIY projects.

What if the air is cool but the house stays hot?

That's useful information. The system may be producing cool air but not moving enough of it through the house. Duct problems, airflow restrictions, and unusual heat gain can all be involved.

When should I call someone?

If you've checked the thermostat, filter, vents, and obvious outdoor airflow and the house still isn't cooling, you've reached a reasonable stopping point. If you smell burning, see smoke, or have any other electrical safety concern, stop operating the equipment. Still not cooling? Find Local HVAC Help