Fogging windshield

A

Adam Helberg

I have the 2002 Outback in S. Calif. and the car is fine except it has a fogging
problem worse than I've had in other cars. When the air conditioner is turned off I
have to keep the fan setting on defog mode to keep the windshield from fogging.

Anyone else finds this a problem?

Adam
 
Adam Helberg said:
I have the 2002 Outback in S. Calif. and the car is fine except it has a
fogging problem worse than I've had in other cars. When the air conditioner
is turned off I have to keep the fan setting on defog mode to keep the
windshield from fogging.

Anyone else finds this a problem?


Fogging means moisture is in the air you are blowing against the windshield.
Warming the air helps some but then warmer air holds more moisture, too.
Typically the A/C gets turned on a bit when you use the Defrost/Defog
setting because the A/C dries out the air. My A/C stopped working years ago
due to a leak which wasn't detected due to long-time non-use which resulted
in damaging several components which made it too expensive to repair. Ever
since then, defogging the windshield takes longer (higher fan setting,
clearing the snow from the vent beforehand, waiting for the heater core to
provide heat to the air) because the A/C isn't helping to dry the air.

Does your A/C work? It's been too long but I recall that the A/C isn't set
to full on when in the defrost setting so maybe it doesn't work well at low
load (so maybe you need it recharged). Are you cleaning out the intake vent
atop the hood near the windshield so you aren't sucking in snow? Do you
even have snow in your area? If it is foggy outside then the air you suck
in is wet, and the A/C helps dry it out. I thought the A/C was supposed to
come on a bit when in the defrost setting. Maybe not in your model which
means you need to manually enable the A/C to dry the air. Blowing humid or
wet air against the windshield is obviously not as effective as blowing dry
air at the windshield regardless of the temperature of the air.
 
Fogging means moisture is in the air you are blowing against the windshield.
Warming the air helps some but then warmer air holds more moisture, too. Typically
the A/C gets turned on a bit when you use the Defrost/Defog setting because the A/C
dries out the air. My A/C stopped working years ago due to a leak which wasn't
detected due to long-time non-use which resulted in damaging several components
which made it too expensive to repair. Ever since then, defogging the windshield
takes longer (higher fan setting, clearing the snow from the vent beforehand,
waiting for the heater core to provide heat to the air) because the A/C isn't
helping to dry the air.

Does your A/C work? It's been too long but I recall that the A/C isn't set to full
on when in the defrost setting so maybe it doesn't work well at low load (so maybe
you need it recharged). Are you cleaning out the intake vent atop the hood near
the windshield so you aren't sucking in snow? Do you even have snow in your area?
If it is foggy outside then the air you suck in is wet, and the A/C helps dry it
out. I thought the A/C was supposed to come on a bit when in the defrost setting.
Maybe not in your model which means you need to manually enable the A/C to dry the
air. Blowing humid or wet air against the windshield is obviously not as effective
as blowing dry air at the windshield regardless of the temperature of the air.

No there is no snow here and hardly any moisture in Orange County. Dry as a bone;
that's why we're prone to fires.
 
Adam said:
No there is no snow here and hardly any moisture in Orange County. Dry as a bone;
that's why we're prone to fires.
Ever notice a sweet smell in your car - like toasted marsmallows?
perhaps you have a leak in the heater core and coolant is causing the
problem?

Carl
 
@newsread1.news.pas.earthlink.net>,
(e-mail address removed) says...
I have the 2002 Outback in S. Calif. and the car is fine except it has a fogging
problem worse than I've had in other cars. When the air conditioner is turned off I
have to keep the fan setting on defog mode to keep the windshield from fogging.

Switch your selector from "recycle" to "fresh"
air.
 
Adam Helberg said:
No there is no snow here and hardly any moisture in Orange County. Dry as
a bone; that's why we're prone to fires.
Check and see if you have a water leak in your heater. That happened to me
several years ago and the windshield would fog really, really bad.

Don
 
My 2K outback has always been a lousy windshield defroster. Even with the
AC on High. Just not quite enough air. I lived in Orange County and I know
you can have some superior fog in the mornings this time of year. I
wouldn't be surprised by a defrosting deficit...Cheer up, though,....other
than that, I love the car!

Jim L.
 
Adam Helberg said:
I have the 2002 Outback in S. Calif. and the car is fine except it has
a fogging problem worse than I've had in other cars. When the air
(snip)

My STi seemed to have a much worse fogging problem than I'd had in other
cars. I used some of that Rain-x stuff they sell for putting on the
/inside/ of the windows and that cured it nicely.

-- Mark
 
Adam said:
I have the 2002 Outback in S. Calif. and the car is fine except it has a fogging
problem worse than I've had in other cars. When the air conditioner is turned off I
have to keep the fan setting on defog mode to keep the windshield from fogging.

Anyone else finds this a problem?

Adam
Just another thought, if the output seems low, perhaps your car has a
cabin airfilter that needs changing.

I dunno

Carl
1 Lucky Texan
 
It's also possible that the inside of your windshield is dirty.
Sometimes, there is a type of dirt that shows up as fog.

Try cleaning it with window cleaner.

After cleaning, you can "wax" it by spreading a very thin layer of bath
soap. This prevents the collection of outgassed plastic from your dashboard.
 
It's also possible that the inside of your windshield is dirty.
Sometimes, there is a type of dirt that shows up as fog.

I will bet serious $$ that this is the OP's problem. Now if I can
just get my SO to clean HER Suby's windshield with this fogging
problem....
 
Carl 1 Lucky Texan said:
Just another thought, if the output seems low, perhaps your car has a cabin
airfilter that needs changing.

I dunno

Carl
1 Lucky Texan

Thanks everyone for all the ideas. I've never had to top off my coolant level so I
don't know if that proves whether there is no leak or not. I've never had any odd
coolant smells inside the car. I'll check the filter and clean the windshield on the
inside.

Adam
 
Here in NW FL cooler outside temps and hi humidity can cause rapid fogging
of windshield. Switching to defogger (A/C cuts in here) can aggravate the
problem as A/C further cools the glass. It makes sense then to add a little
heat when switching to defog, adding or subtracting heat as required.

Rich
 
I do just the opposite, and I never have had a problem. My theory is
that if you recirculate cabin air, the air conditioner will dry it out.
If you bring in fresh air, you will bring in moisture with it, so the
air conditioner has more moisture to deal with.
 
I do just the opposite, and I never have had a problem. My theory is
that if you recirculate cabin air, the air conditioner will dry it out.
If you bring in fresh air, you will bring in moisture with it, so the
air conditioner has more moisture to deal with.

I wonder why the owners manual specifically says not to use the defrost
with the recirculate as it causes the car to fog up???
 
Theodrake said:
I wonder why the owners manual specifically says not to use the defrost
with the recirculate as it causes the car to fog up???

Its a balancing act. If one or more sweaty people with snow covered
boots are in the car for a long time, the internal humidity could be
higher than the humidity outside, so external vent would actually clear
out some humidity. Often extremely cold air is quite dry - so that would
be beneficial. But there are occasions when the outside conditions are
cool and 'muggy', or, after a night of disuse-the inside of the car may
initially be muggy. Under those conditions, running the a/c compressor
and the vent set to recirc. would more quickly clear the windshield.
Even in summer, the inside of the car can become dry enough to irritate
eyes and switching to 'vent' occasionally will allow some moist
(relatively) air in - at the expense of more heat.

Carl
 
Theodrake said:
I wonder why the owners manual specifically says not to use the defrost
with the recirculate as it causes the car to fog up???

Humans are a prodigious source of humidity. Several times a minute we inhale
more than a liter of air and exhale it at more than 90 degrees F and nearly
100% humidity. During winter the cold air has very little moisture, because
it just can't hold it. After all, that is how the A/C dries the air - it
makes the air too cold to hold much moisture.

A window that is completely unfogged in the winter fogs immediately if we
breath anywhere near it.

Mike
 
Typically the A/C gets turned on a bit when you use the Defrost/Defog
setting because the A/C dries out the air.

So it's a cold morning and I've just started the car, turning on the Defrost at
the high heat setting to clear the windshield and warm myself up as well. I've
just turned on the A/C ? ?
 
@comcast.dca.giganews.com>, (e-mail address removed)
says...
So it's a cold morning and I've just started the car, turning on the Defrost at
the high heat setting to clear the windshield and warm myself up as well. I've
just turned on the A/C ? ?

Yup.

Unless you go into your HVAC controls, and detach
the microswitch (single screw) that's depressed
when you rotate the controls over to "Defrost"
position.

Most all cars use that mode, btw.
 
John said:
So it's a cold morning and I've just started the car, turning on the Defrost at
the high heat setting to clear the windshield and warm myself up as well. I've
just turned on the A/C ? ?

Yes, and that's actually a good thing. And you can turn the heater
setting to provide heat, and you'll be mixing refrigerated air with
heated air, and that's OK, too.

In this case, the car engineers really know what they're doing.
 

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