Recommendation? Car windshield problem

annr

annr

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Since the weather turned cold, the interior of the front windshield has been developing condensation, including ice. It’s a pain to get going because one may have to defrost the window exterior AND get rid of the interior condensation or ice which can be difficult.

We took the car to the mechanic, and he said the window seal was fine. We checked that the moon roof was closing, and it seems to be. (We didn’t have this last year—this is our second winter with the car, Toyota Avalon.)

Any suggestions on what the problem might be, how to diagnose it, deal with it?
 
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The heater core is the obvious answer and could very well be the issue. The blower motor could also be the issue. I would also check that the vent and vent channeling isn't blocked. I had that issue on my Jeep. Over time dust, dirt, and debris clogged up the vent causing the condensation on the windshield. Check that first before going the extreme route of the a heater core repair.
 
Here’s one thing I’m not understanding: the pattern of occurrence.

For example, today it is 27 deg F, and the windshield is fine. (The last time the car was driven was 4 days ago. The temps have been in the teens getting as warm as 35 degrees F for the last 4 days.)

Is there a reason the problem could appear intermittent? (Sorry if it self-evident by your replies—I’m just not savy.)
 
Condensate is water vapor coming out of the air. Consistent sub-freezing temperatures result in dry air, so there is little moisture to condense. Get a couple of people in there breathing and the humidity will go up until condensate forms again.

I know it sounds odd, but running the air conditioning will take the moisture out of the air much more quickly than the heater/defroster will.
 
On many vehicles made within the past 20 years, the AC automatically comes on when the "defrost" setting is selected, so be sure you're not accidentally turning the AC off. Have you had any outside precipitation near where the occurrences of the inside window condensation occurred? How old is the vehicle? (You mentioned it's your 2nd winter with it, but not if it was purchased new.)
 
Danke42 said:
  1. Turn heater on at full blast
  2. Turn AC on
  3. Turn off the inside air circulation
  4. Crack open the windows

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Is meant to work on the front and back windows ( just noticed the other day the back window was affected and not the front.)
 
SpyderPhreak said:
On many vehicles made within the past 20 years, the AC automatically comes on when the "defrost" setting is selected, so be sure you're not accidentally turning the AC off. Have you had any outside precipitation near where the occurrences of the inside window condensation occurred? How old is the vehicle? (You mentioned it's your 2nd winter with it, but not if it was purchased new.)
Click to expand...
The vehicle is 11 years old. Last night it rained, and all windows are clear, and I hadn’t noticed a correlation between precipitation and the interior condensation/frost. What would that tell you?

The first time it happened we hit the defrost button, and then we couldn’t figure out if we needed to run the heater, the air conditioning or crack the windows (or all of the above). We didn’t get as far as adjusting the heat or AC (though I didn’t know this about the possibility you mentioned.) Also, the heat is not very hot when the car has been idle overnight.
 
It's more a high dew point and high humidity days than tempuratures that you'll get it I asuume? ... it still could be a small issue with the seal if that's the case.

if not several mentioned good places to start if it has a cabin air filter thats clogged up it can happen ... the heater core is a very likely issue that can cause that too ... and you mentioning the air wan't very warm that might point to the heater core also.

It may be if you're not getting warm air after the car is warm the thermostat could be bad .
 
JJ_Colt45 said:
It's more a high dew point and high humidity days than tempuratures that you'll get it I asuume? ... it still could be a small issue with the seal if that's the case.

if not several mentioned good places to start if it has a cabin air filter thats clogged up it can happen ... the heater core is a very likely issue that can cause that too ... and you mentioning the air wan't very warm that might point to the heater core also.

It may be if you're not getting warm air after the car is warm the thermostat could be bad .
Click to expand...
This seems to happen on cold, low humidity days. The seal checked out ok, and it happens both front and back. (Today it’s 96% humidity, 50 F, and no problem.)

The heat is fine (or seems so) once the car gets going, in a few minutes of driving. I mentioned it because if blasting the heat (like in the video) is key, it isn’t very *hot* when starting the car in 19 deg F temps. (We don’t run the car to warm it up.)
 
the one idea I have is from a friends experience ... his heater core was leaking slightly ... he took pantyhose and put kitty litter in them and left it sit on the passengers side floorboard with the windows open on a warm day ...

it helped and when he took it out got the condensation again so knew it was a leak.

but it sounds like a puzzler as you're trying these things ... and not much is more frustrating than issues with your vehicle.
 
What kind of car is it?
Most cars in the last decade have a blower in the front that does the windsheild, side vents for the front windows, and a wired rear window.

What are the local conditions? Are you getting in with snow on your boots and soaking the floor mats?
 
Danke42 said:
What kind of car is it?
Most cars in the last decade have a blower in the front that does the windsheild, side vents for the front windows, and a wired rear window.

What are the local conditions? Are you getting in with snow on your boots and soaking the floor mats?
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It’s a 2007 Toyota Avalon.

Temps range from the teens to the 50’s. My problem occurrs when the temps hover around or below freezing. No snow involved.

We have the standard features you described. The issue is removing frost and ICE from the interior of the windows.
 
I don’t know if this has any bearing on your situation, check to make sure the drain hose is not plugged. It could be that the condensate is not being drained out and is trapped in the unit. Even though in the winter time there’s very little moisture in the air, it still collects over time. If it doesn’t drain out, it will be blown back into the system. It’s the same as your home A/C-heating system.
It’s worth a look.
 
yablanowitz said:
Condensate is water vapor coming out of the air. Consistent sub-freezing temperatures result in dry air, so there is little moisture to condense. Get a couple of people in there breathing and the humidity will go up until condensate forms again.

I know it sounds odd, but running the air conditioning will take the moisture out of the air much more quickly than the heater/defroster will.
Click to expand...
Would this explain the parked car’s having frost or ice on the interior of the front or back window before even opening the doors or starting it?
 
annr said:
Would this explain the parked car’s having frost or ice on the interior of the front or back window before even opening the doors or starting it?
Click to expand...

The moisture is drawn to the colder temperatures, that explains why the windows freeze up first. Glass is a poor conductor of heat and will cool off before any other material in the interior of the car.
So it’s safe to say that until the moister issue is resolved, the problem will continue. I’m not familiar with Toyota, I don’t know if a heater core leak would be visible. On a Ford or Chevy, I’ve seen a heater core leak show up on the floorboard having damp/wet carpet
 
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Check evaporator drain for clog, broken or cracked door seals/weatherstripping, or maybe you are just bringing in a lot of moisture into the interior (rain, snow, etc.)

A leaking heater core would usually result in leaking on the floorboard and you'd probably be able to smell coolant.
 
Do the kitty litter in socks trick, or a bunch of the silica "Do Not Eat" packs in a sock to help keep the interior a bit drier.
 
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