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Old 03-09-2019, 05:25 PM
bradleyheathhays bradleyheathhays is offline
 
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Problem w/ intermittent defrost a/c

Have a '11 Crown Vic with 290k miles and I've been having a problem with the windows fogging up all the way around. The defrost seems to be working about half the time. On humid rainy days it'll work for say a half hour keeping the windows clear, then the windows will fog hard for 10-15 mins. And then it might decide to start working again, back and forth it goes. When I started it just now the compressor clutch turns when the a/c is turned on, although I haven't had a chance to observe it when the windows are fogging.


A secondary problem it has is that it only blows air through the vents on the front of the dash, straight out into the cabin. The air flows only very weak out the defrost vent at the windshield or the floor. It does this on all settings. Although this might contribute somewhat to the problem, it seems like the a/c does completely cut out as the windows will still fog hard with the a/c set to on and on full fan. When it cuts off the air in the cabin feels immediately humid. One that that helps somewhat is to turn the temp toward cooler and it seems to not fog as much and gives it a chance to maybe clear the fog some.


Any idea what's causing this or what I should do to start testing?
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Old 03-09-2019, 05:56 PM
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dustybumpers dustybumpers is online now
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First things first
Usually when windows fog like that, the heater core is leaking hot antifreeze into the cabin air
You may or may not smell it
Look for wet carpet, etc

2nd
not sure about your car, but on my town car there is a control module that swings the heat/ defrost door open/ closed or middle. they break. to see if it's broken, change from floor to defrost and it will start clicking real bad. you can't mistake the clicking..

Sucky part about both repairs, the dash has to come part away from the windshield to get to the offending parts
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