Hi there, my girlfriend just bought a 1995 chrysler sebring lxi coupe the other day. Great car so far, just one little issue. When driving along, if she turns the fan onto the front window defrost and put it to heat, it fogs up the windows really bad , but if she pushes the a/c button, they clear up. The A/c buton does 2 modes, if you press it once, it goes yellow, if it press it again, it goes green. She just pushes it once when it turns yellow, it works well for defrosting the front windows but if she doesnt have that on it doesnt defrost them at all.

What would cause this?

 

The A/C system not only cools the air, but also dries it. The cold surfaces that the air flows over get moisture on them just like moisture condenses on a cold glass of beer. That's how the air gets dried. That moisture collects in the plenum and drains out the botttom. You have probably noticed water coming out from under the dash area of a car idling with the A/Crunning on a hot day.

If it's cool out and you flip on the defroster, there could be some moisture in the plenum that is sent as warm, moist air onto a cold windshield. Instant fog. Turning the A/C on will helpdry the air. If the temp **** is on Warm, the heater will overpower the A/C and warm the air. Eventually, the warm dried air will clearthe windshield.

You should check the drain for the plenum to make sure it's clear so that the water drains out the bottom as well as possible. That will minimize moisture in the plenum and also minimize bad smells that can result from not drying out.

Sometimes small leaves and stuff from trees collects down there and plugs or slows the drain.

 

Alright, i was just worried about always needing to use the a/c that it would wear it out quicker, thanks for the help. Also the drain plenum is just infront of the windshield on the outside correct? that pops off doesnt it? so it see if there is leaves in there

 

The condensate drain is a hose that comes out of the firewall into the engine compartment and makes a hard turn down, and then ends. It is unlike any other hose or tube coming out of the firewall because all the others run off somewhere else. It's usually made of fairly soft rubber. If you squeeze it gently and it feels like there's something crunchy inside, it is probably full of leaves. The end is usually molded flat so the two sides touch, thus closing the exit so bugs don't crawl in. By "massaging" it a little you can open up the end, crush the leaves and have themfall out.

You don't need to remove the intake grill in front of the windshield to do this. That's a fairly big job involving removal of the wiper arms.

Don't worry about wearing out the A/C while running the defroster. You don't use it that much and it sure beats running into a telephone pole that you couldn't see with the winshield fogged up.

 

Most vehicles now days don't even give you the option of not running the A/C compressor with the defroster. It is part of the system, period. My Jeep is that way, as well as many other cars I have owned.

Compressors last a long time now, and require only a minimum of energy (fuel) to operate.
(General Statement, Not a warranty!)

 

Sorry it took me so long to reply, the webpage on this site would always give me "done, with errors" so i could not type out the message lol. I tried looking for that hose but the engine bay is so cramped i didnt see it. I sprayed the house directly into the intake grill infront of the windshield and the water all came out of the bottum.

But still, unless you press the a/c button, the windows just fog up like crazy, and instantly start to clear up when u press the a/c button. And today it didnt rain out and wasnt humid. Still not sure why it does that, i had an old 93 beretta before and it never did that, also many cars dont come with a/c, so how would you resolve this issue if you didnt have an a/c compressor?

 

Just in case the obvious is being missed; There is also the fact that glass with a temperature difference on each side fogs up. Maybe the glass itself is so cold in the morning that using heat fogs it up and using AC fixes that temperature change.

It sounds like your problem is more drastic than that, but figured I'd throw it out anyway.

MRR

 

Eventually, without an air conditioning compressor, the air will likely dry from the heat that you apply to it when you run the defroster. But the a/c makes it more efficient, and quicker. Also, a blast of moist air on the windshield is a common occurrence when you start the system up. It is condensation that builds up as the heater core cools when you stop or turn the temp control down. Any moisture that runs off the core itself finds that drain you were looking for. Yours is apparently clear. But the core itself still has moisture on it that has not dripped of and found the exit. That's the moisture you blow on your windshield when you start the system.

It sounds like you don't have any mechanical issues to contend with.

Smile!

 

Thanks for all the help guys, much appreciated, heres a few pics of the car in question, my girlfriend just washed and waxed it today

http://i130.photobucket.com/albums/p...l/IMG_0623.jpg
http://i130.photobucket.com/albums/p...l/IMG_0626.jpg
http://i130.photobucket.com/albums/p...l/IMG_0630.jpg
http://i130.photobucket.com/albums/p...l/IMG_0632.jpg
http://i130.photobucket.com/albums/p...l/IMG_0634.jpg

 

Have you checked the heater core for a small leak??

Mike