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Why Is Your AC Blowing Warm Air?

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There's nothing more frustrating than turning on your air conditioner on a hot summer day only to feel warm air coming out of the vents. If you're experiencing this issue, there are several common reasons why your AC may be blowing warm air.

Thermostat Settings

The thermostat settings are one of the first things to check when your AC is blowing warm air. Make sure the thermostat is set to "cool" mode and the temperature setting is lower than the current room temperature. Occasionally, a simple adjustment to the thermostat settings can solve the problem and get your AC blowing cold air again.

Dirty Air Filter

Another common reason for an AC blowing warm air is a dirty air filter. A clogged air filter restricts airflow, making it difficult for your AC to cool the air effectively. Check your air filter regularly and replace it if it's dirty or clogged. This simple maintenance task can improve your AC's performance and prevent issues like warm air blowing from the vents.

Refrigerant Leak

If your AC is low on refrigerant due to a leak, it might not be able to cool the air properly, leading to warm air coming out of the vents. Refrigerant leaks should be addressed by a professional HVAC technician, as handling refrigerant can be dangerous and requires specialized equipment. A qualified technician can locate and repair the leak, recharge the system with refrigerant, and ensure that your AC is running efficiently.

Dirty Coils

Over time, dirt and debris can accumulate on the evaporator coils or condenser coils of your AC unit, reducing their ability to absorb or release heat effectively. This can lead to poor cooling performance and warm air blowing from the vents. Regular maintenance, such as cleaning or inspecting the coils, can help prevent this issue and keep your AC running smoothly.

Electrical Issues

Faulty electrical components, such as a malfunctioning compressor or capacitor, can also cause an AC to blow warm air instead of cold. If you suspect an electrical issue with your AC unit, it's best to contact a professional HVAC technician for diagnosis and repair. Attempting to fix electrical problems yourself can be dangerous and may void any warranties on your system.


If your AC is blowing warm air, don't panic. There are several potential causes for this issue that can be easily resolved with some troubleshooting or professional help. By checking thermostat settings, replacing a dirty filter, addressing refrigerant leaks, cleaning coils, or fixing electrical issues, you can get your AC back up and running efficiently in no time. 

Learn more from a company near you, like Kelly Air Systems / CM Kelly.