air conditioner blowing smoke

What To Do When Your Air Conditioner Is Blowing Smoke


An air conditioner that’s blowing smoke can be the result of several issues, some serious and some minor. In this post, we’re going to take an in-depth look at all the steps you should follow when this issue occurs. 

We’ll begin by taking a look at why this typically happens to begin with.

Why Is My Air Conditioner Blowing Smoke?

Here are the most common reasons.

#1. Clogged Drain Hole

If you have an older air conditioner that’s blowing odorless white smoke, this is a likely culprit.

All air conditioners produce condensation. Newer units collect this condensation in a pan and reuse it for keeping the components cool. 

Older air conditioners, however, have a drain hole through which the water escapes. If this drain hole gets clogged, the water stays trapped in your air conditioner. When the water comes into contact with heat inside your air conditioner, it turns into the steam that you see pouring out of the unit.

While this is one of the more benign types of air conditioner smoke, you’ll still want to get the clog removed by a professional. Also, consider upgrading to a newer unit that makes more efficient use of condensation.

#2. Humidity

If your air conditioner’s internal humidity is lower than that of the air around its vent, you may see a small amount of fog form (read about dew points for a very scientific explanation of this phenomenon). 

Again, this will be odorless and doesn’t pose any immediate risk to your air conditioner or your health. You don’t need to contact a professional to have this dealt with. Instead, let your air conditioner run on high for several minutes. This helps achieve equilibrium between your air conditioner’s internal humidity and the humidity outside.

If this keeps happening, though, you ought to take a closer look at your filter. A clogged filter can exasperate the situation and cause vapor to spew out of your air conditioner no matter how long you keep it running.

Air conditioners in Phoenix should have their filters checked (and possibly replaced) at least once every three months. 

#3. Overheating

If your air conditioning is blowing smoke accompanied by a strange smell, you likely have a more serious issue on your hands than simple condensation. 

Air conditioners are, of course, filled with electrical components. Without proper ventilation, these components will overheat and produce a burning smell. If left untreated, this will evolve into dark, strong-smelling smoke emerging from your air conditioner and perhaps some strange noises.

This type of airflow problem is usually the result of a severely clogged air filter preventing proper ventilation of the unit’s components. 

If you notice this issue, you should immediately shut the air conditioner off and call a professional. Whatever component has been producing smoke will likely need to be replaced and, not to mention the air filter.

#4. A Direct Component Issue

Sometimes, your air conditioner’s circulation may be functioning just fine yet still produce smoke and a strong burning smell. If your air conditioner is on the older side, it’s likely one of the components has gotten worn out and is producing smoke.

Two of the most common culprits are the fan belt (in belt-driven fans) and the fan motor itself.

This type of air conditioning smoke, in addition to smelling terrible, can be toxic for you and the environment. Shut the air conditioner off immediately and get in touch with an HVAC professional. Depending on what component is to blame for the smoke, a professional may recommend replacing your entire air conditioner.

#5. Electrical Failure

Last on our list of reasons your air conditioner is blowing smoke, we have an electrical failure. Faulty wiring or electrical shorts can produce a fire hazard that, in turn, produces smoke and a burning smell. 

Leaving the system running in this condition can be very dangerous. Instead, shut it off, unplug the unit (if possible) and call a professional to have your air conditioner looked at.

Air Conditioner Setting Off Smoke Alarm?

Air conditioner smoke is one thing but there’s also a separate question of air conditioners setting off smoke alarms. This usually isn’t related to smoke from the air conditioner itself but rather a feature in smoke alarms designed to alert homeowners of a power surge.

If your air conditioner’s electrical setup is improperly configured, it may cause a power surge whenever it kicks on. 

When this happens, you should disconnect the air conditioner and call an electrician (or whoever installed the unit). Something is wrong with your home’s electrical wiring and you’ll have the issue intermittently until you fix it.

General Tips for Avoiding Air Conditioning Smoke Issues

If you’ve landed on this page not because your AC is smoking but rather out of curiosity, here are some general tips to help you avoid the issue altogether.

Change Your Filter Regularly

Changing your air conditioner’s filter is very easy and cheap. In addition to preventing smoke, it will improve the air quality in your home. 

While checking and possibly changing your filter is recommended every three months, this is just a guideline. We encourage you to check more regularly if you live in an area with poor air quality. It’s not hard to see when an air filter is dirty, in which case you need to trust your eyes and replace the filter even if it seems to be too early.

Get Yearly Checkups

Find a local HVAC specialist you can trust (we hope you’ll choose us if you live in the Phoenix, Arizona area) and have them perform a checkup on your air conditioner yearly. You might even want to schedule more frequent checkups if you have an older unit.

Checkups will reveal problems that might become serious down the line. It’s much better to deal with those problems on your own schedule before your air conditioner starts billowing smoke.

Get A Properly-Sized Air Conditioner

If you’ve read our article about intermittent air conditioner operation, you’ll know that it can cause humidity issues. These may exacerbate your water vapor problem. 

The most common culprit when it comes to intermittent air conditioners? An oversized unit. Make sure your HVAC professional has installed the correct size of air conditioner. This will save you from a whole host of other problems as well.

Conclusion: Why Is My Air Conditioner Blowing Smoke?

We trust that you’ve found this guide useful. What we’ve discussed here are a few of the most common reasons air conditioners blow smoke. White, odorless smoke often isn’t a cause for major concern, particularly if it’s faint and you live in an area with high humidity.

If thick, black smoke is billowing from your air conditioner, however, you’d be wise to shut it off completely and contact a professional. 

If you live in the Phoenix, Arizona area, we hope you’ll trust us with this and any other air conditioner problems you may have. We’ve been in the business for more than 30 years, helping 50,000+ residents with their HVAC and water filtration needs.

Frequently Asked Questions

Why can I see the air coming out of my air conditioner?

What you’re seeing is condensation formed when cool air from your air conditioner meets warm air in your home. It’s nothing to be concerned about by any means.

What does a bad AC compressor sound like?

A bad AC compressor usually makes a high-pitched or grinding noise. It can also be accompanied by a burning smell or smoke.

What does it mean when your AC is blowing out smoke?

If your AC is genuinely blowing smoke as opposed to just fog, you’ve likely got some sort of electrical problem inside. Switch the unit off and contact your local HVAC repair company for next steps.

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