Why Is My AC Blowing Warm Air?


With Chicago weather always fluctuating, the last thing you need is your unit malfunctioning. Summer can be the best time to sunbathe and tan but not to be inside a humid home. Wondering why your air conditioning is blowing warm air? There could be a variety of reasons why your AC unit is not properly functioning. We at Duct Professor would love to help you self-diagnose the small issues of why your air conditioning is blowing warm air, but if you believe the issue is greater you could always contact us to get a second opinion.

Thermostat Not Programmed Correctly

The most common issue is usually the thermostat is not correctly programmed and is following a set schedule. It may sound foolish, but double-check your thermostat to assure that it is programmed correctly and someone in the house didn’t just accidentally change it. Usually, it is a small fix that you can check on by making sure your thermostat does not say “heat” and assure that your fan is set to auto. When your fan is set to ON, it will automatically turn on without it even cooling which causes the AC to blow out warm air. 

Restricted Airflow 

If that doesn’t seem to be the problem, another issue could be restricted airflow. This usually occurs when your airflow is being blocked inside the vents or has a clogged air filter. This usually happens when your air filter is full of dust and debris which can block the cool air from releasing and is in need of a new replacement. Another thing that could be impeding airflow is obstacles blocking registers and returns, we recommend you check around to assure you are allowing air to flow freely. If that isn’t the problem, it could also be the inside of your vents holding dust and debris. An easy way to check is by removing your return registers, if there is visible dust we recommend you schedule a duct cleaning. It is recommended that a home receives a duct cleaning every 3-5 years.

Low Freon/Puron

One of the last common reasons as to why your AC may be blowing warm air could be that you’re just simply running low on Freon/Puron. Depending on the model and year of your furnace, it could be a quick fix but do not prolong it too long because it could lead to your coil freezing and causing a bigger problem. In this case, we would recommend you contact us to help you with refilling your unit.