Condensation on inside of windshield after having been parked all night

Message: I related to the service advisor at Balise Hyundai ,Hyannis MA that I was experiencing condensation buildup from inside the vehicle on the inside of my windshield at random times after the vehicle had been parked overnight. I was told that there was nothing he could do about it unless he actually saw it. I live approximately 45 miles from the dealership, so by the time I drove there I would have had the defroster clear it off as to have visability to drive. I feel this is a major falt in the vehicle. It happened last night again (random) and I took a short iphone movie from inside to show that i was wiping the condensation off from the inside. I am 72 years old have had many vehicles and consider this a major fault. I would really appreciate any help I could get on this matter. I can understand condensation on the outside that you just clear with your wipers, but inside ? This is not like driving on a rainy or humid day where the windows are affected . THis is a vehicle parked overnight with no one in it and the windshield (inside) is heavy with condensation Thank you,
Whit PS the vehicle is actually an Elantra GT which replaced the touring

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What is your current weather like? If you have snow or rain, with cold temps in the evening, then it warms up outside enough that the interior of the car is comfortably warm, water that you track into the carpet may be evaporating and condensing on the inside of the windshield. The water has to come from somewhere. If the relative humidity is high, such as during rainy times, this would contribute to the effect as well. I would think this would happen more if the car was garaged or parked under a carport or shaded area so the car warms gradually instead of the windshield heating up from sunlight, which would tend to defog the windshield naturally. Also, if you go out to the car fairly early in the day, but before the sun really gets a chance to really warm it up, the windshield would still be cold enough to condense water. (on both inside and outside) Contributing to this may be that the new car has very good seals and is more airtight than your old car, so any water vapor in the cabin doesn’t escape. Maybe try leaving a window cracked and see what happens?

Another possibility is that the heater core is leaking and the vapor is condensing on the windshield. You would notice this though, as it would have a syrupy sweet smell, and leave a slimy residue on the inside of the windshield. Also, it would be hard to get the windows clear with the defroster.

Finally, there could be a water leak into the cabin that is saturating an area where you don’t notice it, providing the moisture that is condensing on the windshield.

It would be nice to know the model year of this vehicle, and whether or not it is still under warranty.
A leaking heater core is a possibility if the car is several years old, but…then again…it could be brand new for all we know.

Could the OP provide the missing info for us?

There is also the possibility that the front windshield needs to be removed, resealed and reinstalled.

If you get into the vehicle with wet boots or clothing, track slush or snow into the car, the interior humidity will be 100% in short order with the windows closed…As night temperatures cool, condensation on the inside of the glass is almost guaranteed…On Cape Cod, the normal humidity is 100% so it doesn’t take much to fog up the windows…

I too thought of the heater core.

Condensation happens when moisture laden (high relative humidity) air comes in contact with a cooler surface. The cooler surface draws heat from boundary layer, and since cooler air cannot hold as much humidity as warmer air, the moisture gets deposited on the surface.

Caddyman is dead right. But if you’ve been losing coolant, a leak in a heater core could add moisture to the air inside the car and exascerbate the problem.

Other possibilities are water leaks: sunroof, vent system, doors, windows, lots of possibilities. Any areas of the carpet or trunk wet?

What model year/miles is your Elantra Touring?

I wonder if the gentleman has his air intake setting for his heater/air conditioner set to “recirculate” rather than to draw air in from the outside?

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My guess is this is a new car or used car that was just detailed and the carpets are sill damp. It will go away with time. Run the AC when you can.

My inside moisture was INSIDE FROST a few years ago as our then new 06 Ford Escape got to the winter months.
new carpets and upholstery—
Snow on shoes brought into car—
hot breath, cold windows----
recirculating air selected—

Not sure what the true cause was since we had never seen this before in any other vehicle we treated in exactly the same manner.

Not sure which one cure procedure worked but we ;
(1) made sure to always set the heater on outside air before parking.
(2) wet vac’d all the mats and carpets.
(3) Ran high heater and defrost fan with windows open a tad.
(4) put school chalk sticks in several places ( like glove box ,door pockets, and under seats. ) as absorbent.

In all the years since, we’ve never had interior moisture or frost again.

Only time I’ve had frost inside the car was when I left the vent set to recirc. Was very odd to grab the scraper and try to do the outside of the windshield only to find out everything was INSIDE. Not a fun thing when you’re trying to get ready to go to work in the morning

I have a 2017 Hyundai Elantra. I have condensation in the front and rear windshields .I also get snow and rain under the doors, when I go out to use the car there is actual snow in cat when I open the door , along with a wind draft as I’m driving it . The wind actually comes under the door , my car only had 3,982 and it’s not a year old . Going to the dealer Sat. Then calling the factory if they don’t resolve this.

Is the vehicle manufacturer really responsible for that feline–with or without snow on it?


Me thinks snow in cat is no longer snow but is water.

:snowflake: :cat:

After FIVE years shouldn’t we have fixed it by now? Yeah moisture inside the car and weather conditions will do that. I have a little moisture in my garage from snow melt. I live about 6 blocks from church and quite a few times after church my windshield will be frosted over. I need to wait for the car to heat up enough to clear the windshield. So its just the high humidity inside the car combined with the morning temperatures. Yeah and it happens on either car so no leak or malfunction. That’s just life in the snow belt.

The underside of the doors are designed to leak a little to make it easier to close the doors w/the windows up. Otherwise the passenger compartment pressurizes during door closings, which opposes your desire to close the door completely. Not every car uses that design. My old VW Rabbit’s doors were air tight, and so was frustrating to close the doors with the windows up. It’s actdually to your benefit that the doors not be air tight, b/c that allows more ventilation, which should help to minimize condensation.

It’s unusual that rain water gets into the car under the doors. There’s other ways that water can get inside the passenger compartment, so make sure to eliminate those as a cause first. For example the doors are designed to allow rain that leaks past the door window seals to go into the door interiors, then any water that gets in is supposed to leak out the bottom of the door and back outside. Perhaps on your car that’s not happening due to the drain holes at the bottom of the door being clogged. Or debris has accumulated on the door sill. When that occurs, water at the bottom of the door can move into the passenger compartment.

Another way rain water can get inside the car is from those air vents directly under the windshield. Any rain that gets into the vents is supposed to drain back out. There’s a water/air separator that allows fresh air inside, but is supposed to drain the water back outside. That separator can become clogged too and divert water inside the car. I had that problem on my truck a couple years ago. I used to get a pile of snow on the floor of my truck sometimes too, when there was a big windstorm at the same time as a snowstorm. It came in through the air/water separator. That gadget doesn’t separate snow from the air unfortunately. But it shouldn’t allow much snow inside the car except like I say in some unusually high wind & snow situations.

Water can get into the trunk area through the tail-light seals too. If you’ve ever had work done to replace a tail light, consider that. And coolant can leak into the passenger compartment via a leaky heater core.

More established car companies have had time to come up with ways to solve all these weird problems. It may be that Hyundai is such a new company of mass produced cars that it hasn’t quite encountered that level of design detail yet. There’s not a drop of rain water getting inside my 25 year old Toyota.

I think it was rather apparent she was talking about a car, not a cat. Can we please not mock people who come to ask questions?

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Hi. Well , you make good points but tonight there has been a down pour of
rain! And the floors are dry no leaks in the windshields ,
when I close the car door , it sounds like it doesn’t close as a matter
fact you really have to push to close it shut, the seal is horrible ! my
civic closed nicely with a solid sound this Elantra is terrible.
I would much rather have an air tight car,that’s what I am use to. I should
not need a three papers towels to dary my windshields.
I have noticed there are many complaints online about the same issue .
Thank you

That is a poor design, there should not be any leaks or drafts from the car doors. The next time we get a Hyundai Elantra in the shop I am going to inspect the door weather strips to see if they left gaps for ventilation, I doubt that they are that poorly engineered. Vehicles built during the last 40 years have cabin vents for the HVAC system.