Common causes
Low refrigerant from a leak, dirty air filters restricting airflow, a frozen evaporator coil, thermostat settings or failures, outdoor unit problems (dirty condenser coils, fan issues), or a failing compressor can all cause warm air from the vents.
Quick checks you can do safely
Confirm the thermostat is set to Cool and a temperature below the room reading. Check that the air filter is not clogged. Make sure vents are open. Look at the outdoor unit to see if the fan is running. If you see ice on refrigerant lines or the indoor coil, turn the system off and switch the fan to On to help thaw—then call for service.
When to call a professional
If simple checks do not restore cooling, avoid repeatedly restarting a struggling system. Continuing to run a system with low refrigerant or electrical faults can cause more expensive damage. Stone Cold Services diagnoses and repairs AC problems for homes and businesses across Southwest Florida.