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Vent expelling vapor when AC ON

8368 Views 7 Replies 7 Participants Last post by  Kaarmaa
My right center vent on an '05 intermittently expels a visible cloud of what seems to be water vapor when the AC is on. Does anyone have any experience with this type of thing?
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On aircraft, the mist is "intentional". Because the air outside is so cold, the cabin would become a freezer if it wasn't heated. However, when air is heated the relative humidity goes down, making the environment uncomfortable, and potential dangerous (static). Consequently, water is added to the air circulation system using a very fine spray. If the air temperature is cool enough, the moisture condenses and can be seen coming out of the vent. It's essentially the same a fog.

With the car, water isn't being added, but cold air is being pushed into the cabin which, on a damp day, could have a lot of moisture suspended in the air. As a result, the cold air causes the moisture to condense, and the same "fog" is formed.

However, I would agree with 1 Lucky Texan on making sure the evaporator drain is working. The same effect as in airplanes could happen if there's an excess of moisture in the HVAC duct.

Otherwise, enjoy the fact that your AC is working very well!
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