Hi Everyone,

 

I've got a 2003 WRX with 124,000 kms that I've owned for two years. As stated in the title, twice this summer on very hot days I noticed faint amounts of water vapor coming from the vents. I don't typically use the the Air Conditioning on anything but the hottest days so I put it down the compressor being a little overworked. I noticed the same thing last night when running the defrost. I didn't see the mist, but my windshield was fogging. Thanks very much for any help.

Dave

During very humid conditions I get that sometimes running up into higher elevations where the cooler air is super saturated with humidity. The fast moving air over the cold core of the AC does leave enough time for the moisture to condense on the coils before it blows out the vents. Very disturbing seeing white mist coming out of the vents when you don't expect it. Seems to mostly happen during the cooling cycle when the compressor is first working to cool the air.

As long as it smells like water, ant not antifreeze, then it's fine. It's normal for the humidity in air to condense into visible vapor when cooled. Like a foggy night after an after noon rain shower.

 

Was the condensation on the windshield on the outside? You know when you take a cold beer out of the fridge, and after a few minutes it starts dripping water off the outside of the bottle?

The defroster vents can make cold spots on the windshield where moisture in the air outside will condense. Moving the temp setting from coldest to somewhere in the middle will keep dry air moving across the windshield inside but it won't cool it enough to make the humidity outside condense and stick to the glass.

As long as it smells like water, ant not antifreeze, then it's fine. [...]

Right, because otherwise there's a heater core leak.

 

Google ''dew point temperature'' for more info.

And for the heck of it, make sure the AC body drain is not clogged.

 

nipper

I've got the same problem. I nearly pooped myself the first time driving down the freeway and my vents started blowing steam.

 

After calming down a bit, I figure its condensation off the evap, as said above. Happens to me every once in a while still, but nothing to worry about. The ac is still up to pressure and doesn't over cool.

 

Dan

I've got the same problem. I nearly pooped myself the first time driving down the freeway and my vents started blowing steam.

 

 

Dan

 

Sheesh i hate to think what would happen if you got a blowout at 60

 

There was a post on nasioc about this the other day. Subaru has a service bulletin about this. A thermosistor or something like that needs to be replaced under the dash for the mist out the vents. It doesn't seem like a quick or easy fix. Mine has done the mist out the vents a few times. I can deal with it. My compressor went out not too long ago, that I fixed, I couldn't deal with no AC at all.

 

I hated that the defroster kicks on the AC compressor. I took apart the AC controls and took out the microswitch that kicks the compressor on when you turn it to defrost. No more foggy windows on defrost.