Recommendation? Car windshield problem

blades&wrenches said:
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.
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This is good to know. The car is from the southwest and the seals and weatherstripping could easily have dried out.

We haven’t noticed anything on the floorboards or smelled anything. The car is immaculate (off white carpet) so anything along those lines is likely to stand out.
 
annr said:
This is good to know. The car is from the southwest and the seals and weatherstripping could easily have dried out.

We haven’t noticed anything on the floorboards or smelled anything. The car is immaculate (off white carpet) so anything along those lines is likely to stand out.
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Some will not leak on to the floor, depending on severity and HVAC case design. Check your coolant reservoir to see if you're losing any, but smell is a dead giveaway.
 
There is no good reason why the lower part of your windshield is constantly freezing condensation. I feel, like others, you have a leaking heater core. As blades and wrenches stated above, check the level of coolant. If it's leaking you'll have a sickening sweet smell. And most of the time they're a bear to get to.
 
Uncle Timbo said:
There is no good reason why the lower part of your windshield is constantly freezing condensation. I feel, like others, you have a leaking heater core. As blades and wrenches stated above, check the level of coolant. If it's leaking you'll have a sickening sweet smell. And most of the time they're a bear to get to.
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I agree this is abnormal. I’m going to mark the coolant level and track it. How long before I should see movement?

However, I have the human nose equivalent of a blood hound’s, and I haven’t picked up even the faintest scent of anything.

Yeah, this looks like a PITA (and expensive) if that is the problem. Is this worth taking to the dealer? (Our local guy already failed to diagnose the problem.)
 
You should be able to find a youtube video that shows taking apart the lower part of the dashboard, that should let you see inside and see if there is anything looking wrong. mouse nests, bits of debris, tracks were water has dripped. you should also be able to remove the cover that goes where the wipers come out, there are some vents in there that might be getting blocked, so a vacuum shoved down there may help. The places I've found mouse nests in cars is shocking.
 
I have no wisdom on this issue. Humidity is usually elevated first thing in the morning (except when it gets very cold) which is why you get the icing. You might notice that in most cases, frost forming on your roof or yard grass tends to happen first thing in the morning which tends to be the coldest temperature at the highest outside air humidity. This is a very interesting thread by the way and I hope you discover what is causing the issue without much cost.

Out of curiosity, have you turned off the AC (button) on the dash even though you are mostly using heat? I have done this, but modern cars use the AC system for the defrost function for both hot and cold conditions. The difference between different days has to be outside humidity and temperature issue.
 
gadgetgeek said:
You should be able to find a youtube video that shows taking apart the lower part of the dashboard, that should let you see inside and see if there is anything looking wrong. mouse nests, bits of debris, tracks were water has dripped. you should also be able to remove the cover that goes where the wipers come out, there are some vents in there that might be getting blocked, so a vacuum shoved down there may help. The places I've found mouse nests in cars is shocking.
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Good idea! unfortunately, you overestimate my abilities—substantially. I will take look to see what I can learn.
 
22-rimfire said:
I have no wisdom on this issue. Humidity is usually elevated first thing in the morning (except when it gets very cold) which is why you get the icing. You might notice that in most cases, frost forming on your roof or yard grass tends to happen first thing in the morning which tends to be the coldest temperature at the highest outside air humidity. This is a very interesting thread by the way and I hope you discover what is causing the issue without much cost.

Out of curiosity, have you turned off the AC (button) on the dash even though you are mostly using heat? I have done this, but modern cars use the AC system for the defrost function for both hot and cold conditions. The difference between different days has to be outside humidity and temperature issue.
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Yes, this has been a bit of a puzzler (for me anyway). After looking on Toyota forums, I see the question crops up often enough. This is my first experience in decades of car ownership…

You are right it is some combo of temperature and humidity, and I would love a less invasive, low cost solution. Fingers crossed. At least now I have some ideas to try.

The car was used extensively yesterday, and this morning: frost everywhere but NOT the interior windshield.

I don’t tinker with the defrost preset, which includes AC.
 
I worked on a car once that never got the chance to fully warm up, the owner literally drove three blocks to work (bad knee, slight hill, winter in canada) and the whole car was soggy from never getting the chance to dry out properly since the AC or heat never fully got working. The engine oil was sludgy with water since the engine never got above 212F to boil the water out. So maybe its just a matter of some days, the humidity building up during short trips, then getting just the right temp over night? Frost could start near the vents because that is where the window tends to be the dirtiest, and the frost needs something to form onto. Again, just trying to throw out some ideas that might not be major repairs.
 
gadgetgeek said:
I worked on a car once that never got the chance to fully warm up, the owner literally drove three blocks to work (bad knee, slight hill, winter in canada) and the whole car was soggy from never getting the chance to dry out properly since the AC or heat never fully got working. The engine oil was sludgy with water since the engine never got above 212F to boil the water out. So maybe its just a matter of some days, the humidity building up during short trips, then getting just the right temp over night? Frost could start near the vents because that is where the window tends to be the dirtiest, and the frost needs something to form onto. Again, just trying to throw out some ideas that might not be major repairs.
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Thanks. I’m going to track it a bit. Called the former owner and they NEVER had this problem or heard of it. Condensation is one thing, frost and ice are intolerable.
 
You're lucky you could talk to the former owner. That is an option most don't have. I believe that I have only had heavy frost/ice on the inside of my windshield once. I ran the engine with defrost until it finally melted. I don't believe it has ever happened with one of my Toyota's and I have owned one constantly since 1980. Oops.... slight break in time line as I sold my Toyota and my wife got some crappy new car that turned out to be an absolute lemon. After a year, we got rid of it and I got another Toyota pickup and she took over driving my small GMC Jimmy (at the time).
 
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Thinking back about the limited times I have had interior windshield freezing in the winter.... I may well have left a window cracked on those occasions as it is a common practice of mine, especially in the summer.
 
22-rimfire said:
Thinking back about the limited times I have had interior windshield freezing in the winter.... I may well have left a window cracked on those occasions as it is a common practice of mine, especially in the summer.
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Funny thing: some of the advice I read said to leave the window cracked to prevent the problem.

Our initial impression was that the moon roof was slightly cracked open causing the problem.

Either way, no problem the last 3 days even with freezing temps. (Hard to test theories on an intermittent problem. But it sounds like yours was.)

BTW, previous owner was dear old dad—so not hard to get an honest answer. He replaced the Avalon with a current model and sold it in under a year—hates the way it rides with the low profile tires. I offered to return this car—which they clearly miss—but no. Their favorite is their late model Lexus and the have a rav4 for winter. No interior icing on any of them.
 
annr said:
I agree this is abnormal. I’m going to mark the coolant level and track it. How long before I should see movement?

However, I have the human nose equivalent of a blood hound’s, and I haven’t picked up even the faintest scent of anything.

Yeah, this looks like a PITA (and expensive) if that is the problem. Is this worth taking to the dealer? (Our local guy already failed to diagnose the problem.)

You asked, how long before you should see movement, if any, on the coolant overflow tank?
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Depends. Depends on how much you drive the vehicle. Patience.
Like the baby bull and the papa bull looking at a bunch of cows up on a hill. Baby bull says to papa bull, let's run up there and have one of them. Papa bull said no son, let's walk up there and have them all. :)
 
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