Smoke Coming From Vents When AC Is On

Man Looking in an HVAC Air Vent

The cooling system is a crucial component of your home’s comfort. You might be wondering what you should do in case a problem arises. If the air conditioner is blowing smoke, determine if there is also an air conditioner smell. This article helps you figure out potential problems. However, it is still best to consult an air conditioning technician, so all serious or potentially dangerous issues are ruled out. They have the trained eye to determine why smoke is coming out from the vents when the air conditioning system is on.

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Air Conditioner Blowing Smoke: Causes & Solutions

Read on to learn about the typical culprits behind the smoke coming out of the vents when the air conditioner is switched on.

AC Condensation Accumulating In The Heater Box

condensation from air conditioner

If white smoke is coming out of your vents, it is likely that it isn’t really smoke. There’s a good chance that it is condensation, especially if it doesn’t have any smell.

Air conditioners pull in warm air, which is then cooled, naturally resulting in condensation. If condensation accumulates in the heater box, the condensation could turn into vapor and get released with the cooled air. As a result, white smoke or fog escapes from the air conditioner vents. A blocked drain line can be what causes the excess water in the heater box.

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Cold Dry Air Comes In Contact With Warm Air

White fog typically forms when cold air hits warm air, especially if the warm air is highly humid. This is like when you go out on a cold day, and you see your breath. When warm, moist air comes into contact with cool, dry air, condensation or water droplets form, and you will see them as fog or white smoke.

One of the common culprits behind this issue is that the air conditioner doesn’t have proper airflow. Try turning on your air conditioner to cool your home faster and help lessen the problem.

Moreover, ensure that air filters are cleaned or changed regularly. Having a professional HVAC contractor conduct yearly air conditioner inspections can help ensure you have a properly-functioning cooling system at home.

Air Conditioner Drain Hole is Clogged

air conditioner condenser

Many newer air conditioner models aren’t equipped with drain holes, but older ones usually do. The evaporator coil of the air conditioner generates condensation as warm air is cooled. This condensation needs to drain. The condensate drain line helps drain the water outside, far from your cooling unit. However, the drain line can get clogged as time passes, and this can cause the water to back up into your air conditioner. White vapor is generated and released on the air conditioning vents when this happens. Regular air conditioner tune-ups can help avoid drain line problems.

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Failure Of An A/C Component

An air conditioner has become a staple in many homes because of its convenience. However, it is often put under heavy strain. An air conditioner is often burdened to keep up with the cooling demands during the summer season.

It is only natural that the air conditioner’s components eventually fail as the system ages. If the air conditioner utilizes a belt-driven fan, smoke can come out due to a failing fan belt.
The fan motor might have also burnt out. If the smoke coming out the vents has a foul smell, turn the air conditioner off immediately as this smoke can be toxic. Contact a qualified HVAC technician to diagnose and repair the problem. Sometimes, the best solution is to replace the aging air conditioning unit.

Overheating Air Conditioning Unit

woman plugging nose due to smelly air conditioner

If the white smoke has a strange smell, it is likely that the problem is more severe than mere condensation. An air conditioner is made of several electrical components that can overheat, especially if air doesn’t flow properly throughout the air conditioner.

A dirty HVAC air filter or clogged vents can be the problem. Make sure to turn off the air conditioner immediately and call a trained HVAC technician to prevent the problem from escalating. An HVAC professional will determine which part/s are overheating. These components likely need replacing before the air conditioner can be safely used again.

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Air Conditioner Electrical Problems

A wiring problem is another reason there is smoke coming from the air conditioner’s vents. Your cooling system consists of many wires and electrical connections. If even one of them is faulty, they can release smoke and bad odor.

Again, remember to turn off the air conditioner right away when it is emitting a strange smell. An electrical problem can be very dangerous. It can even cause a fire if ignored. A trained HVAC professional is needed to fix this problem.

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Is Your Air Conditioner Setting Off The Smoke Alarm?

air conditioner setting off smoke alarm

It can be a little unsettling when your smoke alarm goes off. However, it is likely not a smoke issue that’s causing it. Generally, a power surge can be the reason behind your air conditioner setting off the smoke alarm.

Unplug the air conditioner or pull the air conditioner’s circuit when it happens. Call a professional afterward. The issue is likely caused by how the air conditioner was installed. It could also be due to a problem with your home’s electrical system.

Is The White Smoke Coming From Your Air Conditioner Odorless?

Take action when you notice smoke coming from the vents of your air conditioner. Determine if the smoke has a foul smell or is odorless. If it is the latter, there’s a high chance it is a condensation issue. However, you still shouldn’t ignore the problem as an air conditioner that’s not draining properly can cause other problems.

If the white smoke has a bad smell, it is likely because of a failing component or an electrical problem. It is crucial that you turn off the air conditioner immediately and contact a trained HVAC technician in both cases.

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How To Avoid Smoke Issues With Your Air Conditioner

There are several steps a homeowner can take to ensure that their air conditioner functions as intended. The first one is annual air conditioner maintenance. An HVAC professional will inspect the cooling system for any signs of trouble. They will also repair the problems before they escalate into bigger ones. Moreover, simple tasks like regular air filter replacement can go a long way in preventing issues.

Another problem that many homeowners overlook is the size of the air conditioner. An air conditioner that is too large or too small for the space can be problematic. Consult an HVAC professional if this is a concern.



It is crucial that you are aware of any cooling system problem you might have. The first sign of a problem, like white smoke coming out the vents of your AC, means that it is time to call a professional HVAC technician. There are some issues that are not as dangerous but could still result in higher air conditioner repair costs down the road. Other air conditioner problems could be hazardous and should be dealt with right away. A trained HVAC technician can assist you in this area.

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Point Bay Fuel provides top-notch HVAC services in Ocean and Monmouth County, New Jersey. We hire only the best professionally certified technicians who can conduct all your excellent heating and cooling service needs, including boiler tune-ups, air conditioner repairs, ductless installations, and more. Each tech has the right tools, knowledge, and experience to promptly and accurately service any HVAC system.

Rest assured, our company has one of the most competitive HVAC service rates in the locality. Our maintenance services help improve comfort, air quality, and energy efficiency while reducing your home’s energy bills. We can recommend the best heating and cooling repair or replacement system for your home and budget. All our work comes with a guarantee because your satisfaction is important to us. To schedule a service appointment, give Point Bay Fuel a call today. We offer in-home estimates.

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