What is wrong with my defroster?

[blurredvision]

Car is a 2008 Dodge Charger. This has been happening over the past couple of months but I want to describe what happened on my way to work this morning. I have the fan on as high as it will go, the heat on as hot as it will go and the fans blowing towards the windshield only.

While the car is warming up and idle, everything seems fine. Windshield clears, side windows clear. Once I get in and head down the road, changing nothing in regards to heat or the fans, the windshield starts to fog over around the edges and top, and will stay this way. The side windows will fog over completely and this morning, with the 11 degree temp, the side windows even frosted over on the inside, even though I was literally sweating from having the heat up and on full blast.

Can anyone give me a hint as to what's going on?

 

[exdeath]

Turn on the AC while the heat is on to dehumidify the moisture in the cabin caused by your breathing.

If that doesn't work your heater core is probably leaking.

There is moisture present and it must be removed regardless of hot or cold air.

 

[blurredvision]

Turn on the AC while the heat is on to dehumidify the moisture in the cabin caused by your breathing.

If that doesn't work your heater core is probably leaking.

There is moisture present and it must be removed regardless of hot or cold air.

Thanks for the response. If turning on the AC with the heat works, does that mean anything is wrong or is that just what I'm going to have to do moving forward?

 

[jolancer]

those are symptoms of heater core leak but usually that won't be the case unless your driving an old beater that was not taken care of. and if it were leaking theres other symptoms that go along with it, like odd smells and engine over heating sometimes.

if AC fixes your fog, there is nothing wrong
if AC Does NOT fix the fog, there still might not be anything wrong except your AC may not be working

11*F? as in 20 bellow? thats cold... if the vent is set to recirculate it will fog up if AC off. if your vent intake near your windshield wipers are frozen over/blocked it will fog up with out AC.

my vent is usually froze over.. and I don't like turning my AC on, so i point the side heater vents at my side windows, and crack my side windows just a hair so fresh air comes threw there... sometimes windows are froze over too have to use AC sometimes till warms up... YMMV depending on vehicle and environment

 

[LTC8K6]

Yes, you want the compressor running to reduce humidity. Almost all modern cars run the compressor anyway when defrost is selected, even if you do not push the A/C button.

 

[heymrdj]

Yes, you want the compressor running to reduce humidity. Almost all modern cars run the compressor anyway when defrost is selected, even if you do not push the A/C button.

This. Most vehicles you'll see the A/C light turn on automatically to dehumidify the air, it's practically a requirement for good defrosting.

So on that note, make sure when it's on that the A/C is actually cycling. You system could be damaged and the compressor may not be turning on. You should be able to easily hear the click on and click off of the compressor, as well as the change in engine noise as it loads and unloads.

 

[blurredvision]

This. Most vehicles you'll see the A/C light turn on automatically to dehumidify the air, it's practically a requirement for good defrosting.

So on that note, make sure when it's on that the A/C is actually cycling. You system could be damaged and the compressor may not be turning on. You should be able to easily hear the click on and click off of the compressor, as well as the change in engine noise as it loads and unloads.

The more you know....thanks gentlemen.

 

[phucheneh]

The A/C light won't even always come on. But the compressor is engaged. If you can't hear it kick on when you turn the defrost on, check under the hood. The A/C compressor should be pretty easy to locate, and it's obvious whether it's running (front face of pulley stationary versus rotating).

 

[SparkyJJO]

Or it could be too frickin cold for the compressor to kick on. AC systems can freeze over and at least on older cars the defrost with the temp setting above a certain level would never kick on the compressor.

My first two cars had shot AC systems (compressor wouldn't even spin on the one) and the defrost with heat still worked just fine. No defrost unless I had the heat blasting which sucked on rainy humid spring days 😛