Air conditioners are a lifesaver during the scorching hot summer months. However, when an AC starts to blow warm air instead of cool, it can be frustrating and uncomfortable. With some advice from the experts at American Home Water and Air, weโ€™ve put together the top issues and potential reasons for air conditioners blowing warm air.

Dirty Air Filters

Dirty air filters are the most common cause when it comes to AC units blowing warm air. If the air filter is clogged with dirt, dust, and debris, it can restrict airflow, making it difficult for your AC to keep your home properly cooled. Changing your filter at least quarterly will prevent this from happening. During periods of heavy use or if you have pets, you may want to change your air filter monthly.

Refrigerant Leaks

Refrigerant cools the air that passes through the AC unit. When there’s a leak in the refrigerant lines, the AC system won’t be able to efficiently cool the air and will blow warm air instead. If you suspect your refrigerant is leaking, youโ€™ll need to call a professional for help rather than trying to handle it yourself.

Dirty Coils

Condenser coils located in the outdoor unit of your AC system help release heat from your home. If these coils are dirty, they canโ€™t do their job and youโ€™ll feel warm air blowing from the AC. Clean your condenser coils regularly to prevent this problem. If you have routine maintenance performed, your HVAC technician will do this for you as part of the service.

Faulty Thermostat

A malfunctioning thermostat can cause an AC unit to blow warm air. If your thermostat is reading the wrong temperature or not functioning correctly, it may cause your AC unit to turn on and off irregularly, resulting in warm air blowing. Contact an HVAC technician to repair or replace it.


If you’re experiencing any of these issues with your air conditioner, it’s likely a good idea to contact a professional technician who can diagnose and repair the problem. This ensures you experience minimal downtime and get your AC back to working condition ASAP!

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