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Why is My Air Conditioner Blowing Out Smoke? A Phoenix Tech Answers

2021 Apr 16
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Have you noticed smoke coming out of your AC vents? You might be worried about what’s causing it.

Although we can’t say for sure what the cause is without an in-home inspection, a number of common culprits could be at play, including:

  • A dirty air filter

  • Clogged drain hole

  • Problem with the blower fan

  • A refrigerant leak

  • Age of your AC

Below, we’ll take a look at why these problems happen to help you find the best way to fix them.

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Culprit #1: Dirty air filter 

If you see white misty smoke coming out of your AC vents, don’t worry. The white misty smoke is just water vapor and can be resolved by replacing your air filter.

AC systems remove not only heat but also humidity from your home’s air. When cold and dry air meets warm and humid air, condensed water vapor forms. 

When an air filter gets clogged, warm indoor air is blocked from entering your AC system and being dehumidified. This causes cold and warm air to come into contact with each other, which creates condensation. 

To fix: Switch out your air filter as soon as possible. We recommend changing your air filter at least every quarter.


Culprit #2: Clogged drain hole 

One of the perks of having an AC system is that it also lessens the humidity in your home. However, the moisture has to drain somewhere, and if your external drain hole is clogged, the extra condensate will create fog. When backed up in your AC ducts, this fog will start to billow out of the vents inside your home.

Sometimes after a storm (especially during monsoon season here in Arizona), there will be dirt and other yard debris that clog your drain hole. Other times, mold and mildew buildup are the culprit.

To fix: If you’ve already checked your air filters and suspect a clogged drain hole is at play, it’s best to have it looked at by an HVAC professional immediately. Depending on the cause, the vapors can be dangerous to inhale, particularly if you have mold allergies.

For additional reading, see our previous post: My Air Conditioner’s Drain Line is Clogged. What Do I Do?


Culprit #3: Problem with the blower fan 

The blower fan is what pushes cool air out through your vents. If it starts to malfunction, the fan’s speed will slow and cool air will linger. As this cool air comes into contact with warmer air inside your home, it condenses into white smoke.

Often referred to as steam or fog, the effects of a malfunctioning blower fan are nearly identical to that of a clogged air filter or drain hole. However, you can tell it’s a blower fan issue if you put your hand up to the vent and can feel that the air isn’t blowing very hard. 

To fix: Have an HVAC professional perform a tune-up on your AC system. Prevention is the best remedy as your technician will be able to replace faulty parts before they turn into bigger issues.


Culprit #4: Refrigerant leak

If you’ve noticed an increase in your utility bills as well as your AC starting to blow warm air, it’s likely a refrigerant leak.

Refrigerant is a chemical agent inside your AC that cools your air. When refrigerant levels are low, your AC won’t be able to fully cool your air, causing increased humidity and white smoky air.

To fix: Call a licensed HVAC technician for an inspection. Refrigerant is a toxic substance and should only be handled by a professional. 


Culprit #5: Age of your AC

If your AC is more than 10 years old, it could be blowing out smoke because of mechanical issues.

Sometimes as AC systems age, parts begin to break down. You could have a motor that’s past its prime, and just isn’t able to keep up with the cooling needs of your home. If this is the case, you’ll have warm and cool air mixing, creating white misty smoke. 

To fix: It’s best to get your AC replaced. Even though it can be an investment to replace your AC, your monthly energy bills will decrease due to improved system efficiency.

If you’re not sure what’s causing smoke to blow from your AC, call a George Brazil technician. Upon inspection, they’ll help you determine the cause and how best to fix it.


Want help from a Phoenix AC pro? Contact George Brazil.

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Available 24/7, one of our trustworthy technicians will come and inspect your AC and answer any questions. With upfront prices, warranties, rebates and flexible financing options — we’ve got your AC repair covered.

For more information, visit our central AC repair and ductless AC repair service pages. We also offer an AC maintenance plan, to save you money on AC repairs.


Related reading:


Should I Replace My Central Air Conditioner? A Phoenix Tech Explains.

Where Is My AC Filter Located and How Do I Change It?

Why Is There Black Stuff Coming Out of My Air Conditioner Vents? A Phoenix Tech Explains.