Steam from vents

Basic AC theory here. Air has moisture in it, i.e. humidity. You didn't say, but I will bet you don't live in the desert!.

Before the air can be cooled, the humidity is lowered . That is where all of the water comes from under your car while the AC is running, (same thing in your house)

What happens in some systems is a bit of ice forms on the expansion coil. When you turn the system off the ice melts but doesn't necessarily drain away. It can get trapped in the air cooling box. When you AC is turned on again the cool air blows across the warm water and it enters the cabin as fog. It should only last a few seconds. If it lasts longer than that you have clogged/pinched drain line on the evaporator.

This was a common phenomonem in early Honda Accords. Don't know if current models still have this feature. I have also seen this on some GM cars with climate control systems that run the AC all the time and add heat to maintain a specified temperature. I don't have any idea what the air box/evaporator configuration is on either example. Never really checked it out since I didn't own those cars.

hope this helps,

chuck petterson

I had a terrible scare when a plane I was on landed in Washington National Airport on a summer day. Just after we touched down, what looked like smoke poured out of the air vents. I settled down in a mment, when I realized there was no smoke smell, and I decided the "smoke" was moisture from the outside air that condensed into fog when it came into the cool air in the plane.

It could also be a leaking heater coil, better get that checked.

The car is a 850 turbo I haven't done anything different and after taking the car in for a/c service and it is cold but the steam is annoying!! The vent is on recirculate and it still the glass fogs up. Ill take it in again but the last time I brought it in they told me it steams because it is operating at its best possible..

Your drain may be clogged, causing excess condensate to accumulate in the unit. If you start noticing small water droplets coming out the vents, it's time to clear the drain. A piece of #14 copper wire works, just round off the end a bit.

Gary