Why Is My AC Running But Not Blowing Cold Air?

An AC running but not blowing cold air usually points to restricted airflow, low refrigerant, or a thermostat/control setting problem. The most common cause we see is a clogged air filter that starves the coil of air and can let ice form, so the system runs but won’t cool the house. This issue is common and typically repairable after proper diagnostic testing; if the indoor blower runs but the outdoor fan never starts, a weak capacitor is a frequent culprit. Our technicians regularly diagnose these problems in homes throughout the Saint Augustine area using professional meters and safe troubleshooting steps. Del-Air Heating, Air Conditioning, Plumbing and Electrical also offers a $29 A/C tune-up plus whole-home temperature assessment.

• Replace a dirty or collapsed filter and make sure all supply/return vents are open.
• Set the thermostat to COOL and AUTO; ON can blow room-temperature air nonstop.
• If the outdoor unit runs but the larger copper line isn’t cold or sweaty, stop and schedule service.

Turn the system off if you see ice on the refrigerant lines and let it thaw before restarting to avoid compressor damage.

Updated: 2026-06-18

Need help in Saint Augustine, FL? Call (904) 310-7355 or book online.