How to stop windshield from icing up on the inside

[Pyral]

Every time I try going somewhere and its below freezing out, the windshield always becomes translucent to opaque because water condenses on it and then freezes. I've never seen a car that did this so badly.

Sometimes I get in the car and it's already like this, but even worse my breath will condense on the glass as I'm driving because the engine hasn't warmed up enough.

Things that I've tried that don't work:
RainX- useless against condensation in cold weather.

Desiccant packs- stops water deposited on floor mats from evaporating and condensing, still does nothing for moisture in your breath immediately condensing on contact with the glass.

Deicing spray- It only loosens the ice, once it soaks into your rag it will refreeze on the glass. Also causes streaking and makes a mess.

Running the AC before I turn the car off- does nothing when your breath is the source of moisture.

Opening the windows when driving- in theory this should flush out the humid air with frigid dry air. But it only makes me miserable.

Ice scraper- the concave inside glass means that unless your scraping it horizontally (really hard to do when seated), it'll never make good contact with the window.

Any ideas on how to stop this?

I will install a coolant block heater this spring so the coolant will be warm when I get in, but it's too cold right now. And I'm not willing to sit around waiting for the engine to warm up.

 

[pavelvoivoda]

Assuming everything works on your 4Runner, assuming you have manual HVAC controls, it may seem counter intuitive, but if you turn the fan ON, switch to cold, open the air vent so outside air can get in and turn the knob to windshield defrost vent, this problem should disappear within a couple of minutes. There should be an icon on the vent control - if you look closely, you'll see it says "USE WITH" and points you to use outside air vent when the windshield option or windshield and foot option is selected. The AC will turn automatically regardless if you turned the AC switch ON (you can hear the engine rpm change when idling at a traffic light for example), and will dry the windshield intermittently. The condensation from the air is collected and drained out when it makes contact with the AC evaporator when air is recirculated back thru the vent under the passenger dash or is directed thru the rear trunk vent on the left fender. You can see the condensation drain under the car behind the front right tire on a left hand drive 4Runner.

For this to work, all these should be in good working order:
-The ac blows cold - ac compressor will not start when the car is full of cold air, but will start if you switch to one of the "USE WITH" icons on the left knob.
-the temp select knob should adequately change temp - ask someone to change temperature and observe the heater valve moving located directly under the hood above and behind the motor.
-the outside air vent should be opening without obstruction
-air should blow thru the vent for the windshield located in front of the dash when the fan is on
-the back rear left fender vent in the trunk should not be obstructed.


Having the ac turn on from using the "USE WITH" icons on the vent control, should also help warm up the engine faster as more loads are turned on (ac compressor)

If your Runner has manual controls, that's how you clear the windshield. If you have autoclimate control, someone else please share as non of my 4runner have this option.

 

[JohnMc]

Using recirc is one common mistake, so common that as pictured above, they put a reminder on the controls.

Also, if there's a lot of moisture in the car to begin with, it can be hard to keep that from condensing on cold windows as it warms up. Sunroof or other leaks making the carpets damp? Tracking in snow that melts into the carpets? Heater core leaks (you'll usually smell a sweet smell inside the car)?

 

[brillo_76]

Using recirc is one common mistake, so common that as pictured above, they put a reminder on the controls.

Unless your heater core is half plugged.. Then the recirc is great when its below 20 degreese out... However, you are correct always best to pull outside air in.

 

[MaineRunna]

If you have ice on the windows inside your car it's because of an abnormally large amount of moisture inside your car. Your problem is more a water intrusion problem than a heater problem.

 

[Devbot]

^^ this. If there's no obvious puddles than most likely one of your seals is going out or something, maybe rear cabin vent is bad and letting in moisture being kicked up off the road. You could try throwing in some heavy duty desiccant packets around and leave it overnight or over the weekend too - look into Sundry-II by Rexxam. Those things would protect raw steel shipped through the amazon and are color indicated once they stop working (shift from white to brown). If things improve after that - great. If not, it could be indicative of water entering somewhere
I had ice on the inside of my windshield the other day, but that was because a bottle of water spilled in the back. After one or two days the moisture was gone and I didn't have the issue again, even when temps dropped to 8 degrees. Clearly moisture is getting in somewhere in your case. If it's snowy in your area and the air is dry as a result, it's gotta be from it melting at some point I would think

 

[Pyral]

If you have ice on the windows inside your car it's because of an abnormally large amount of moisture inside your car. Your problem is more a water intrusion problem than a heater problem.

No mystery there, water intrusion problem would be from snow melting off my boots and puddling on the plastic floor mats. I hit my boots together before getting in, but I can't eliminate it completely. It causes less problems for me since I started keeping desiccant packs around. I don't like it, but this source alone has never been bad enough to be a danger to drive with, even when it's -20C.

I have the same style of manual controls as [MENTION=111373]pavelvoivoda[/MENTION] but mine doesn't have the "use with" diagram. Probably a 99+ thing. I never used recirculate but I'll try turning those vents on immediately instead of waiting for the engine to heat up.

 

[alumarine]

If you move the Recirc lever back and forth can you hear the baffle make a thunk thunk noise that would indicate it's working.
Thunk is a technical term...

 

[gamefreakgc]

Having the A/C on when using the defroster will help it clear moisture off the windshield faster. Reason being is that the A/C compressor will dehumidify the incoming fresh air and help combat the moisture in the vehicle. It's not going to solve it completely but it does help. More modern cars automatically turn on the A/C when you switch to defrost.

 

[alumarine]

Having the A/C on when using the defroster will help it clear moisture off the windshield faster. Reason being is that the A/C compressor will dehumidify the incoming fresh air and help combat the moisture in the vehicle. It's not going to solve it completely but it does help. More modern cars automatically turn on the A/C when you switch to defrost.

3rd gens and I believe 2nd gens do turn the A/C on when set to defrost.

 

[3bears]

mine no longer has ac. But I live in a very dry climate so dont get the moisture in vehicle. But when I lived in Oregon, where it is wet, the ac was critical to defrosting ( different 3rd gen that had ac)

 

[phattyduck]

I never used recirculate but I'll try turning those vents on immediately instead of waiting for the engine to heat up.

Not that a Southern California boy should have input on this, but...

You'll definitely want to always have air flowing to the windshield. This will deflect the warm moist air from your breath away from hitting the windshield in the first place.

Unless it was disabled (you can unplug the connector for this on the back right corner of the manual HVAC controls), the AC should be on whenever either of the two defrost settings are on. It will not turn on the AC light, but it will be active. Big but here though - that doesn't happen below freezing. There should already be "zero" (ha!) moisture in air if it is below freezing.

It may just be that you are much closer to the windshield in the 3rd gen - most other modern vehicles have a windshield much farther away.

-Charlie

 

[Corrin Bran]

I had something similar due to a clogged cabin filter. It didn't let in much outside air. And before a cold night, it's better to open the windows and turn off the heater about 10 minutes before you park at home.

 

[phattyduck]

I had something similar due to a clogged cabin filter. It didn't let in much outside air. And before a cold night, it's better to open the windows and turn off the heater about 10 minutes before you park at home.

Clearly not a 3rd gen owner... there's no cabin air filter.

-Charlie

 

[Blackgoat]

Every time I try going somewhere and its below freezing out, the windshield always becomes translucent to opaque because water condenses on it and then freezes. I've never seen a car that did this so badly.

Sometimes I get in the car and it's already like this, but even worse my breath will condense on the glass as I'm driving because the engine hasn't warmed up enough.

Things that I've tried that don't work:
RainX- useless against condensation in cold weather.

Desiccant packs- stops water deposited on floor mats from evaporating and condensing, still does nothing for moisture in your breath immediately condensing on contact with the glass.

Deicing spray- It only loosens the ice, once it soaks into your rag it will refreeze on the glass. Also causes streaking and makes a mess.

Running the AC before I turn the car off- does nothing when your breath is the source of moisture.

Opening the windows when driving- in theory this should flush out the humid air with frigid dry air. But it only makes me miserable.

Ice scraper- the concave inside glass means that unless your scraping it horizontally (really hard to do when seated), it'll never make good contact with the window.

Any ideas on how to stop this?

I will install a coolant block heater this spring so the coolant will be warm when I get in, but it's too cold right now. And I'm not willing to sit around waiting for the engine to warm up.

If you have a 1998 it has the old style radiator and its a wonder your getting any heat outta it!! I would seriously move to FLORIDA :bluejump:

 

[Pyral]

If you have a 1998 it has the old style radiator and its a wonder your getting any heat outta it!! I would seriously move to FLORIDA :bluejump:

Radiator was replaced, heating actually works very well once the engine warms up. I'm fine with the cold, I'm fine with heat, but I'm not fine with humidity; I could never live in Florida.

I haven't retrofitted in a cabin air filter, so there isn't one to get clogged

 

[Mendoncyclesmith]

No mystery there, water intrusion problem would be from snow melting off my boots and puddling on the plastic floor mats. I hit my boots together before getting in, but I can't eliminate it completely.

I was heading right here.

The WeatherTech or similar "pan style" things are awesome, but this is the other half of the coin with them.

I run venta-shades on all my windows, have for years. Allows me to crack all 4 door windows, and all that nice, warm, readily evaporating water in the front "buckets" now has an escape route.

What doesn't, freezes faster due to more cold air getting in, and that reduces the evaporation time slot too.

Other than that, your defroster doesn't work, I take it?

 

[Pyral]

Other than that, your defroster doesn't work, I take it?

The rear defrost kinda works, some of the lines are broken, but I have the paint to repair them. The front defrost works.

 

[Mendoncyclesmith]

The rear defrost kinda works, some of the lines are broken, but I have the paint to repair them. The front defrost works.

Yeah, I'd invest in a way to improve "non operational phase" air exchange.

Huge issues with footwell "buckets" and fully closed windows. Add those vent shades, leave my windows cracked, problem just stoped.