Why Is My AC Running But Not Cooling Properly?

An AC that runs but isn’t cooling usually has an airflow blockage, a refrigerant issue, or a control fault. The most common cause is a dirty filter or a matted outdoor coil that starves airflow. Heavy heat gain from attics or sun-soaked rooms can also make a good unit feel weak. One field cue: if the outdoor fan runs but the compressor keeps clicking, airflow or low charge is likely. We handle these calls daily throughout Chesterfield and surrounding areas. Preferred Partner Plan members save 15% on repairs and receive two system checks a year starting at $19/month.

Try these quick checks:

• Set thermostat to Cool, fan Auto, and 3–5 degrees below room temp.
• Look for ice on refrigerant lines or the indoor coil; if you see ice, turn the system off to thaw and call for service.
• Check for a full condensate pan or tripped float switch; a clogged drain can stop cooling while the fan runs.

If basics are right and cooling still lags after a new filter and a gentle outdoor-coil rinse, schedule a diagnostic to prevent bigger damage.

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Updated: 2026-02-13

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Need help in Chesterfield, MO? Call 3148148455 or book online. Air Comfort is easy to work with, reliable and efficient. — Jacqueline G.