Hi everyone, I have a 2004 5AT TL.

I've noticed this issue on and off for about two years. Front windshield glass was replaced about a year with PGW glass, rear and sides are original OEM, no aftermarket tint, etc.

I've noticed my TL holds a lot of moisture in the vehicle, the side windows will just have a little bit of fogging and the front and rear glass are getting iced up on the inside. Tonight was especially cold, -16 degrees Celsius (3 degrees Fahrenheit), and my front glass was completely iced up inside and my rear glass was iced up as well. The door windows were pretty much unaffected. I even find when its close to freezing temperatures, I'll get a little fogging in the TL when parked, even for an hour or two. Looking back, even when it would be humid and rainy outside during the spring/autumn weather (mild out, but not hot), I would get fog building up on the windshield and I would have to put the AC on to dehumidify the vehicle.

I've seen many people say online that putting kitty litter in a container or sock, etc will help absorb some of the moisture, and I found that helped a little bit when it was around freezing and just below, the fogging on the glass was reduced a little bit, but tonight it didn't help at all.

I'm sure this issue isn't related to the TL only, but I haven't had this kind of issue in previous vehicles and I was just wondering if anyone else had this issue and hopefully be able to find a solution to resolve it. Thanks in advance.

 

 

That shouldn't be happening if you have the air on high and the recirculation off. The only think I can think of is that maybe the vents behind the rear bumper are frozen shut or otherwise not opening correctly. But even then, the air will find another way out. The car's not air tight.

Try cracking a window, cranking the air on high and max heat. If you still have the problem after that then I'd be stumped.

 

No, I let the system work itself on Auto and just regulate the temperature. The only time I'll turn re-circulation on is if I'm going through a dusty area, and I'll turn it off right afterwards, or if the system wants to run re-circulation on it's own accord, which usually happens the when it's very hot out.

I've tried cracking windows when leaving it parked, and it made a very slight difference, but there's still major humidity in the vehicle when I come back. I've ran the heat on high a few times especially to accelerate the defrosting of the windshield and no matter what I do it seems like it'll clear up but it's only temporary as when I park the car and come back there's some humidity on the glass depending on the temperature. If it's not too cold, then there's just fog on the glass on certain spots, etc. but when it's gets colder the front and rear glass definitely ice up inside.

I figured the car isn't air tight so why isn't the moisture not leaving on its own. I didn't even know we had vents in the rear bumper but that may be something worth following up on.

 

Pull the carpets up wherever you can and check for wetness. Sounds like something is maybe retaining moisture in the cabin

 

This...for sure. We had a vehicle that had similar issues...there was water under the carpet in the back due to an unknown water leak in the rear hatch. Something is introducing extra humidity into the cabin...either a water leak or possible heater core....although you should be able to smell the heater core if it were the culprit.

 

OP, are you sure that the compressor is cycling? Sounds to me like it's not doing it's job. Even if you had some kind of source of excess moisture, your windows shouldn't have ice form if the compressor is doing it's job...

 

I don't have any funny smells or anything as I am always looking out for smells and noises coming from the vehicle while driving. If there's a leak it may be small, I'll have to take out all the mats and everything and take a look/feel to see if anything is wet or damp as that would help explain what's causing the issue. I agree about something introducing humidity though because when I run the defroster it has no issues dehumidifying and keeps the car humidity free while it's running. If i turn it off of defrost and go back to regular heat, I find the sometimes the glass does start to slowly fog up depending on the wetness and temperature outside.

In the spring/autumn, I can usually crack the windows a bit while driving and that will help clear it up depending upon conditions, but turning on the defrost will eliminate the fog in literally seconds.

The compressor kicks on and cycles no problem. I can hear it kick on and off while it's running. The ice is forming while the vehicle is parked, no major build up while driving around.

Tonight was a similar temperature as yesterday, there was some ice but no where near as yesterday. Once again, the side windows were all clear, the front and rear were iced up some. Thanks everyone for all the help so far.

 

Just pulling the mats and feeling the carpet may mislead you. The carpets have a rubber membrane backing which may be completely soaked between the floor pan and the backing but be dry above. Removing door sill trims and pushing you hand under the carpet in as many places as you can is your best bet. The carpet can also be gently pulled back a bit where the driver and passenger feet are up front.