When your air conditioner runs but blows warm air, the usual suspects are a dirty air filter restricting airflow, a tripped breaker on the outdoor unit, a frozen evaporator coil, low refrigerant from a leak, or a thermostat set to the wrong mode. Replace the filter and check the breaker first. A frozen coil needs time to thaw with the system off. Refrigerant and electrical issues require a licensed technician — don't try to recharge refrigerant yourself.
This article is general guidance, not a substitute for a licensed technician. When in doubt, call (866) 803-4910 and we'll connect you with a local pro 24/7.