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Discussion Starter #1
Hello guys,

New to the forum. Been noticing lately that while driving & the AC is on, smoke will come out of the left-center vent for a few minutes then goes away. There is no burning smell but this is more of a nuisance smoke when the AC is running. This 1st happened occasionally about a month ago but now is becoming more frequent. Also the AC doesn't seem ice-cold at times either. Could this be an upcoming major problem on my LX? Currently have 7,800 miles on the car

- Will
 

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You sure it's smoke and not fog/consensate? Does it leave water forming around your vent? Certain temp combinations can cause this when it's real hot. Not an issue if this is the case.
 

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Discussion Starter #3
No water around the vent, has been quite warm/hot in MI. Hard to tell if its smoke or condensation, but lasts for a few mins then goes away
 

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Are you using Auto climate control setting? Is it humid where you are? This is just condensation most likely. You may need to adjust your HVAC settings to compensate for whatever is causing the condensation. If it's very humid, running in Recirculate mode might help. And make sure your temp is not set too low.
 

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Discussion Starter #5
I'll give the auto setting a try. Usually have the temps set between 70-75 both sides. Can get quite humid at times during the summer months here in MI
 

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Science! First, the A/C uses a refrigerant to make something called an evaporator very cold. An evaporator looks like a very small version of the radiator in the front of the car. It has fins. It also gets cold and is part of the HVAC system. As hot humid cabin air passes through the evaporator, that air cools rapidly. As the air cools, its temperature falls well below its dew point and the water vapor (invisible) in the air is forced to condense into droplets (dew). At the bottom of the evaporator is a holder into which that water accumulates and usually drains out of a tube under the car. As the air passes through the evaporator it gets colder (and drier) and then passes back into the cabin through the air vents (supply).

When that air passes through the evaporator, sometimes it does not have enough time for all the condensed water to accumulate on the evaporator. Some of those water droplets remain suspended in the air as fog. Fog gets created when the air temperature falls below the dew point and the dew (water droplets) has NOT yet settled on a surface. Those water droplets remain suspended in the air – fog.

As long as the air that leaves the evaporator is below the dew point, it can support the fog. That fog is what you see as “smoke” as it gets blown out of the vents into the cabin. But it doesn’t stay as fog for long. As that cool air mixes with the hotter air inside the cabin, that cold air rises back above its dew point and the water droplets evaporate back into vapor – invisible humidity again. This all happens quickly, like within a few inches of leaving the air vents.

However, after running the A/C for a few minutes, the humidity inside the car falls to the point that the A/C no longer creates fog. (The combination of temperature, humidity and air pressure changes.) That is why the fog only lasts for a few minutes. In effect the air in the car is drying out. In the end there is no problem. Any car can and will do this given the proper temperature, humidity and air pressure conditions.
 

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I was gonna post a Terminator meme with something like "Your car has become self-aware" and is trying to kill you, but after reading "Baldeagle"'s most excellent explanation- I am going with what he said.
 
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Science! First, the A/C uses a refrigerant to make something called an evaporator very cold. An evaporator looks like a very small version of the radiator in the front of the car. It has fins. It also gets cold and is part of the HVAC system. As hot humid cabin air passes through the evaporator, that air cools rapidly. As the air cools, its temperature falls well below its dew point and the water vapor (invisible) in the air is forced to condense into droplets (dew). At the bottom of the evaporator is a holder into which that water accumulates and usually drains out of a tube under the car. As the air passes through the evaporator it gets colder (and drier) and then passes back into the cabin through the air vents (supply).

When that air passes through the evaporator, sometimes it does not have enough time for all the condensed water to accumulate on the evaporator. Some of those water droplets remain suspended in the air as fog. Fog gets created when the air temperature falls below the dew point and the dew (water droplets) has NOT yet settled on a surface. Those water droplets remain suspended in the air – fog.

As long as the air that leaves the evaporator is below the dew point, it can support the fog. That fog is what you see as “smoke” as it gets blown out of the vents into the cabin. But it doesn’t stay as fog for long. As that cool air mixes with the hotter air inside the cabin, that cold air rises back above its dew point and the water droplets evaporate back into vapor – invisible humidity again. This all happens quickly, like within a few inches of leaving the air vents.

However, after running the A/C for a few minutes, the humidity inside the car falls to the point that the A/C no longer creates fog. (The combination of temperature, humidity and air pressure changes.) That is why the fog only lasts for a few minutes. In effect the air in the car is drying out. In the end there is no problem. Any car can and will do this give the proper temperature, humidity and air pressure conditions.
Can you be a little more specific next time :D
 
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