Foggy windows... Is this common .

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candymancan
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Foggy windows... Is this common .

Postby candymancan » Thu Nov 08, 2018 4:41 pm

Obviously Virginia is a humid area in pretty much all seasons and in my ZJ i can just flip on defog and the windows defog... but thats only if the A.C is filled and working.. because on modern vehicle to defog the inside of a car you need heat and a.c to take moisture out of the air.

On the wagoneers the defog is just heat.. And while it may work slowely on the windsheild all the other windows gets foggy... I can drive and have every single window including the rear foggy from just my body heat.. and defog does nothing except the windshield.

I found if i crack at least 2 windows down a little then the windows will defog.

Is this normal ? Im assuming it is because defog on these Jeeps doesnt use the a.c just heat and pure heat just causes more fogging.. I can replicate it in my ZJ if i turn the a.c off when defog on.. the windows will all get foggy
2013 SS camaro, cammed, and modded too much to say 500 RWHP/650 crank 30k
1998 Jeep Grand Cherokee 5.9L Limited 191k
1998 Jeep Grand Cherokee 4.0 I6 laredo 256k
1990 Jeep Grand Wagoneer 126k

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Stuka
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Re: Foggy windows... Is this common .

Postby Stuka » Thu Nov 08, 2018 10:04 pm

It typically means you have a small leak someplace in the Jeep. Normally through the cowl vent. That water then evaporates when temp and humidity is right, and fogs all the windows. My Cherokee did it bad, cleaning all the debris out of the vents down by your feet so that water could drain down and out helped. My J10 does it because the windshield seal has a slight leak.

And yeah, cracking the windows gets the air flowing and defogs.
1981 J10 AMC 258 with HEI and Weber 32/36 DGEV Carb, T176, NP208, D44/M23 with 4.56 gears and Detroit Locker, 6" lift, 33x12.50 Cooper STT's, BJ's Offroad Rear Dozer Bumper.
2017 JKU Rubicon Lifted and stuff
Pevious Jeeps: 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

SJTD
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Joined: Tue May 21, 2013 12:02 pm
Location: Lompoc, Sunland or somewhere between

Re: Foggy windows... Is this common .

Postby SJTD » Fri Nov 09, 2018 8:54 am

It's a poor 50 year old design.

The heater/defroster pulls in outside, often humid air. There's no recirc so it's a continual process. Heating the windshield defogs it but all that humid air still gets on the others as you've observed. Leaks Stuka mentioned make it worse.

Turning on the AC will dehumidify the inside air. Idunno whether it'll be enough.

I guess that's why they added the tailgate defrost. Easier than redesigning the climate control.

Reminds me of trips to Florida. Hot, humid. Windshield fogged on the outside in the corners because the glass was cold.
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.

candymancan
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Re: Foggy windows... Is this common .

Postby candymancan » Fri Nov 09, 2018 9:20 pm

Leaks as in water leaks.. I deff dont have those anymore I had leaks thrpugh the windsheild gasket. my quarter panel window. and the door but thats been fixed.. it can pour from a hurricane and i see no leaks anywhere now.

My cowls vents dont leak either but i never did clean the debris if any from them.. Ill check. I know after i fixed my leaks yes the windows fogging up didnt happen as much anymore.. but it still happens. Onve thr Jeep has been runnig for abit and im driving it doesnt happen anymore.. But i sware for the first 30 minutes give or take it fogs up so badly... and if i close the windows i cracked down eventually i cant see out of any window... If i crack two down then i can see out of all the windows.

zbut the rear one.. which is like always foggy.. and with my heating elemebt not working ( too lazy to fix it.. the relay and power works i just need to use a blow to4ch and solder the wires on as the previous owner tore them off.. I found cracking the rear window down a tad helps lol.

Thank god the heat in the Jeep gets TOO HOT like burns you hot.. so i dont notice the cold air coming in from tje cracked windows.

Uhg what a pain especially when it rains out

Im wondering if its just a bad design in the air conditioning.
2013 SS camaro, cammed, and modded too much to say 500 RWHP/650 crank 30k
1998 Jeep Grand Cherokee 5.9L Limited 191k
1998 Jeep Grand Cherokee 4.0 I6 laredo 256k
1990 Jeep Grand Wagoneer 126k

SJTD
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Joined: Tue May 21, 2013 12:02 pm
Location: Lompoc, Sunland or somewhere between

Re: Foggy windows... Is this common .

Postby SJTD » Fri Nov 09, 2018 10:36 pm

The bad design is the AC being separate.

The defrog air doesn't go through the evaporator to be dehumidified before exiting the vents.

Youse has the integrated controls so it isn't obvious but the heat and AC are totally separate and independent systems.
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.

candymancan
Posts: 1844
Joined: Tue Mar 22, 2016 11:32 pm

Re: Foggy windows... Is this common .

Postby candymancan » Sun Nov 11, 2018 9:35 pm

Yea i figured like in my first posy... had a feeling its because the a.c doesnt run with the heat to dehimidify the interior like on a modern vehicle
2013 SS camaro, cammed, and modded too much to say 500 RWHP/650 crank 30k
1998 Jeep Grand Cherokee 5.9L Limited 191k
1998 Jeep Grand Cherokee 4.0 I6 laredo 256k
1990 Jeep Grand Wagoneer 126k


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