Why Is My AC Blowing Smoke?

Summer is officially here, and in Arizona, that means AC is a necessity. When the thermometer starts crossing into triple digits, the last thing you want to see is your AC blowing smoke, but don't panic. This isn't always a major problem, and an HVAC tech may be able to diagnose and repair the issue the same day. Some potential reasons for smoke coming through AC vents include:

Learn how each of these can cause your AC unit to start blowing smoke and what the fix is below.

You're probably wondering how a dirty air filter could cause smoke to come through the AC vents, but sometimes, the smoke isn't actually smoke. In some cases, it can be water vapor that comes out like a mist or fog that people mistake for smoke. A dirty air filter is a potential cause of this phenomenon because the evaporator coil of your AC unit can freeze without proper airflow. A dirty vent hampers the airflow. Once the evaporator coil is frozen, it will start to thaw when the unit is off, which can produce water vapor.

This is the best-case scenario because all it takes to fix it is letting the evaporator coil fully thaw out and replacing the air filter.

A clogged drain line can create a problem similar to the one described above. The drain line is a simple piece of your HVAC system, but it's very important. As your AC unit runs, it creates condensation, and the drain line is how that condensation is removed from the unit. If the drain line gets clogged, the condensation has nowhere to go and blocks airflow. This can cause the evaporator coil to freeze over and cause the same blowing mist issue as above.

An HVAC tech can quickly diagnose a clogged drain line and clear the clog so your system can go back to operating efficiently.

The blower fan is one of the primary components of your AC. It's responsible for moving air throughout the entire system, which is what keeps your home cool. If there's an issue with the blower fan, it can cause the evaporator coil to freeze. This may eventually result in it blowing water vapor as the coil thaws. However, it's possible for an issue with the blower fan to cause the motor to overheat and potentially cause an electrical issue, which could then result in actual smoke coming from the unit.

If you think smoke is coming from your AC unit, shut the system off and call a repair company as soon as possible to prevent a larger safety issue.

Refrigerant leaks can lead to smoke coming out of your AC unit for two reasons. The first is that it can lead to the evaporator coil getting too cold and freezing over, which causes the issues discussed above. However, a refrigerant leak can also cause a more serious issue. AC refrigerant is a strong chemical, and if it leaks onto any of the unit's electrical components, it could cause a fire and look like smoke blowing out of the unit.

AC units are complex systems, and sometimes, it's not initially clear why they're blowing smoke. An HVAC technician can evaluate your system and quickly diagnose the issue so you can get back to cooler temperatures as soon as possible. At George Brazil Heating & Cooling, our techs will provide you with a full explanation of the issue and a quote for repair, including an estimated timeline, so you have all the information you need to make a decision.