Ice on windshield interior

No that’s impossible. When you park your car at night just make sure you put the heater on “floor” as opposed to defrost or dash. If you’re not sure how to do this see your owner’s manual.

I would add as an after thought, do you usually bring a nice warm cup of coffee into the car with you, and while it’s warming up, the coffee is steaming up the windows? (thus making more ice)

The ice inside the car is indicative of too much humidity inside the car. this humidity can come from the coffee cup, your breath, or your dog.

reducing the moisture is the key. all the ways mentioned are likely to help. but in my opinion, making sure the recirculate button is off is probably the most important. you actually want fresh air coming into the car, to “dilute” the high humidity inside the car.

This is the downside to communicating this way. I’m not sure why I would put the heater on floor. Do you mean that in the morning it will be ready to blow on the floor?

Yes, actually, it would be. IN the morning when you run the heat, select DEFROST again. At night, when you put your car to bed, select floor so the air/moisture in the system evaporates out onto the floor rather than the window. Then when you get in to start up the next morning you will have to select DEFROST again.

Ensure the fresh air vents (below the windshield) are free of debris and (at this time of year) snow and/or ice.

Blocked vents will not allow fresh air to be drawn into the cabin and with the ice and/or snow blocking them will supply you with moisture (into the cabin) as a restricted amount of air is drawn in.


Don’t be, their weather is sometimes worse than ours up here.

FYI, 12F is -11.11C Yep, cold no matter which thermometer.

I’m deeply appreciative to all who’ve responded!! Many thanks for taking the time to write.

Ummm, I did.

There’s no need to go through all that vent shifting.

Put the defroster on first thing and run it on high speed and high heat untill you can see through the windshield safely (the A/C runs at the same time as ‘defrost’).

Then switch the air to split between the windshield and the floor or between you and the floor.

That way,while you are driving, the floor and wet shoes/boots are drying out at the same time.

Next day start out with defrost as I said.

I do this all the time and have never had ice on the inside of the windshield.

Oh, the joys of cold weather driving. Assuming you?ve fixed your ventilation control issues, here?s a sure fire tip to fix your problem:

Open your windows and air out your car when you?re finished at the end of the day. Sounds crazy but:

  1. Warm air holds more water vapor than Cold air. When the car cools down, all that water vapor condenses and freezes on your windows. Therefore, your car may be clear when you start but all fogged/iced up the next day. A weather change to much colder weather can also ice up your car without you doing anything.

  2. This is made worse by a number of things including older cars that might be a bit leaky, snow melting on the mats, coffee, post workout sweating, spouse that talks too much, etc.

If you park your car outside and it?s a safe area, pick a day when you know there will be no snow/sleet/rain and open your windows a crack. It will air out overnight. Even if there is ice on the windshield when you get home. Chemistry/Physics thing I don?t want to put you to sleep.

There are a couple of ways that I like to do this. When I unload the car at the end of the day, I leave the hatch/doors open for a while and then close them when I lock the car up. If I?m in a rush, I?ll open with windows a bit on the home stretch to blow out of the car (not always effective). The best method though is to leave the windows open a bit overnight.

You can also try windshield treatment stuff like Rain-X antifog and other products like that at Autozone/PepBoys/etc.

Good luck. If all else fails, keep a good scraper and some paper towels handy.

Thanks for the suggestions! Actually, I drive home from work with all the windows slightly open, for all the good it does. Can you explain how leaving the windows open a bit on cold Winter nights wouldn’t ensure interior window freezing? Thanks again for your help.

O.K. here goes. Hope you have a cup of coffee…

Have you ever left your ice cube tray in the freezer forever without using it (winter time)? Of course, nobody uses ice cube trays anymore so toss an ice cube in the freezer and see what happens over time. When you finally take out the ice cube tray, there’s no ice and it seems like the ice evaporated? It’s because they did (sublimation). Basically, water is constantly going changing from one state to another. Gas to solid, Solid to gas, liquid to gas, gas to liquid, etc. What helps is with the windows open, very dry cold air will prompt the ice on your windows to “evaporate”. Something about seeking equilibrium. Some Chemistry/Physics PhD will do a much better job explaining this. Read this:

Opening your car windows allows the dryer cold air outside your car to flow into your car and “dry it out”.

Thanks for the quick response. I’m headed out the door to crack the windows! Why do you say no one uses ice cube trays? I have four which are in constant use! Many thanks again for your help!

When my brother had a VW bug he periodically had to leave the windows open a crack overnight to get rid of interior iced up windows. He said it always worked like a charm. And VW bugs weren’t known for having great heaters/defrosters.

I appreciate the advice. Thanks!

If you are having significant ice on the inside of the windshield you could have other issues going on, such as a leaking heater core, or a blocked AC drain line. I think you might want to have a mechanic look into it, if it is the drain line it will be a cheap quick repair with a blast of compressed air. If it is a heater core it could cause the car to over heat due to loss of coolant. You do not say what kind of car this is by the way. Some cars are more prone to this than others. Do you detect a “moldy” oder in the car (indicating a blocked drain line) or a sweet smell indicating a bad heater core?

Thanks for your input. I have a Suburu Outback. There are no unusual odors, nor is there an icy build up on a regular basis. I’m not sure what’s going on. Thanks again.

I had a 93’ Dakota that did the same thing. The problem was the seal around the windshield leeked. Do you get condinsation in side the windshield durring the summer at night or early morning?

I haven’t had the car for that long so I can’t say.

If your windshield wasn’t fogging up on the inside during warmer weather, then you probably don’t have a leaking heater core.