Why Is Smoke Coming Out Of The Vents When AC Is On?

image of an hvac air vent

The cooling unit of your house is an integral component of your family’s comfort, but what steps should you take if you notice unusual performance, such as AC noises or other oddities? For example, if you notice that your air conditioner blowing smoke, take a pause to establish whether there’s a smell too. In this article,  we discuss prospective air conditioner issues. It is important to note that you should always employ the health of HVAC technicians to eliminate any severe or likely dangerous scenarios. They can utilize their expertise to establish the cause of any smoke emanating from vents when the air conditioning unit is turned on.

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Air Conditioner System Discharging Smoke: Probable Causes & Solutions

Below, we will be looking at some of the common causes that make smoke emanate from vents when the AC unit is turned on.

AC Condensation Accruing In The Heater Box

condensation from air conditioner

If you notice what appears like white smoke emanating from the air conditioning vents of your house, there’s a very high probability that it isn’t really smoke to begin with. Chances are that it’s just condensation, particularly if you see it’s white fog. However, you should note that it’s scentless.

As your AC system absorbs warm air, the air gets cooled which subsequently causes condensation. If the condensed air accumulates inside the heater unit, it’s not bizarre for the condensation to convert into a vapor that gets out with the cooled air, which forms that fog or white smoke emanating from the air conditioning vents. This additional water in the heater unit could be due to a drain line that’s clogged.

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Air Conditioner Cold Dry Air Making Contact With Warm Air

When cool air makes contact with hot air, particularly if the hot air has high humidity levels, it’s not surprising to see white fog develop. This is similar to when you go outdoors on a chilly day and your breath is visible. The heated, moist air that engages with the cold, dry air results in water droplets or condensation that will become evident as fog or white smoke.

A frequent reason for this issue is when your cooling system isn’t receiving adequate airflow. To assist in mitigating this issue, try changing your air conditioner on high to cool your house hastily; also, ensure that the HVAC air filters are replaced or cleaned on a regular basis. Having an annual air conditioner tune-up done by a certified HVAC technician can assist in ascertaining that your cooling unit is working optimally.

Air Conditioner Drain Hole is Blocked

clogged condensate drain for air conditioner

Most of the latest air conditioning units don’t come with a drain hole, but previous models generally do. The evaporator coil in the air conditioning unit generates condensation as the heated air cools. The condensation formed needs draining. The drain lines allow the condensate water to get out of the unit, away from your air conditioner. Still, as time lapses, it’s likely for this drain line to get blocked, which can lead to the condensate getting back into the AC unit. When this occurs, white smoke is usually discharged from the  air conditioning vents. Routine air conditioner maintenance can assist in preventing issues with the drain line.

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Malfunction Of An Air Conditioning Component

An HVAC unit has become a common amenity in a majority of households today. However, this contemporary convenience is usually placed under very heavy strain. Keeping pace with the cooling needs of your house during the scorching summer months can take its toll on the air conditioning unit.

As the cooling unit depreciates with time, it’s expected that the internal parts will eventually break down and stop working. If the fan of your cooling system is belt-driven, indications of smoke could arise from a malfunctioning fan belt.

The failure may also be a result of the motor in the fan overheating. If you smell something foul and you see smoke emanating from the AC vents, it’s integral that you switch off the HVAC system right away. This kind of smoke can really be lethal. A professional HVAC contractor should be consulted to diagnose and resolve the issue. At times, your best course of action might be just replacing your old air conditioner.

Overheating Air Conditioning Unit

man plugging nose due to smelly air conditioner

If you see white smoke that comes with a weird odor, the issue is most probably more severe than simply condensation. An air conditioner unit has various electrical parts, and these parts can burn up, particularly if there’s no adequate air circulation to the cooling system.

Clogged vents or a blocked air filter might be the issue. If you experience this scenario, it’s crucial that you switch off the air conditioner right away and get in touch with a reliable HVAC professional to prevent the problem from escalating. Your HVAC contractor will inspect the unit and establish which part(s) is overheating and will most likely need to do a replacement before the cooling unit can be utilized again safely.

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Air Conditioner Electrical Issues

Another possible reason why your A/C unit may emanate smoke from its vents is if there’s an issue with the wiring system. The cooling unit comprises several electrical and wire connections, however, if one component malfunctions, it could result in smoke and a bad smell.

Again, when you smell something strange, it’s a sign that you need to switch off the air conditioner right away. An electrical problem could potentially be very hazardous and result in a fire outbreak if left ignored. This is a dangerous issue that will need the skill set of a professional HVAC contractor.

Is Your Air Conditioner Triggering The Smoke Alarm?

air conditioner setting off smoke alarm

Although it may be a bit worrying to see the smoke alarm of your house blow up, it’s likely not a serious problem when the smoke is just setting off the alarm. Typically, if your AC unit is triggering the smoke alarm, it’s due to a power surge.

If you’re experiencing this issue, disconnect the air conditioner system or unplug the circuit for the system and enlist a specialist. Chances are that there’s an issue with how the air conditioner was fitted or you have an electrical problem.

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Is The White Smoke Emanating From Your Air Conditioner System Unscented?

If at any moment you see smoke emanating from the AC vents, taking action immediately is of the essence. The first thing to ascertain is whether the discharged smoke is unscented or has a bad odor. When the smoke is unscented, chances are that your air conditioner has a condensation issue. This doesn’t suggest that you should leave the issue unattended as an air conditioning unit that’s not draining water correctly could result in other problems.

At the same time, if you smell a bad odor accompanied by white smoke emanating from the air vents, you are likely dealing with a part that is malfunctioning or an electrical problem. Either way, the best thing to do in that situation is to switch off the unit and get in touch with an HVAC technician.


How To Prevent Smoke Problems With Your Air Conditioner

There are numerous actions a homeowner can take to make sure their AC unit is working at full capacity. This usually begins with yearly HVAC maintenance. A professional HVAC technician will use their know-how to evaluate the cooling unit for indications of trouble and repair any issues before they escalate. Also, easy tasks, like doing an air filter replacement routinely can help in avoiding any prospective issues.

One issue that most individuals overlook is the Air conditioner’s size. An air conditioning unit that is too small or big for your house can eventually result in issues. Make sure to consult with your HVAC contractor if you don’t know what air conditioner size to go for.

It’s essential that you identify any potential issues with your cooling unit. The first indication of concern, like fog or white smoke emanating from the vents, suggests it’s time you call a pro HVAC technician. Some of the issues you encounter may not necessarily pose a danger but could result in huge HVAC repair costs in the long haul. Some air conditioner issues are dangerous and should be handled right away. Enlisting licensed HVAC technicians is the best option to help you.

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Contact Wilcox Energy For All Of Your HVAC Needs


Wilcox Energy provides first-rate cooling and heating services on the southern Connecticut shoreline. We have employed the best-licensed HVAC contractors in the market who can deliver top-tier HVAC replacements, installations, repairs, and tune-ups. Every one of our technicians has the know-how and skillset to service your HVAC unit properly.

Wilcox Energy offers the most affordable cooling and heating service costs in the region. Our expertise can enhance your comfort, and minimize your house heating and cooling expenses while increasing your energy efficiency. Our number one priority is customer satisfaction which is why we stand behind all our projects. To book an appointment, call Wilcox Energy now to get a complimentary, in-house estimate.

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For more information about heating and cooling systems, be sure to contact Wilcox Energy. You can contact us at (860) 399-6218. We offer a full line of heater and air conditioner repairs, maintenance services, and installations.

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