Heat from windshield defroster and fogging for no reason

[hyde]

Sometimes when it is just about right temperature outside, i notice my windshield starts getting foggy near defroster grills. When I touch it, I notice there is some heat coming out of there. Is that supposed to be doing that? The A/C, Heater, etc is OFF. Is that the heat that is coming from the engine somehow gets routed inside through those grilles, into my windshield? For example yesterday, it was about 70* and it did it again.

 

[JeepJeepster]

Yup, Ive always noticed that too.

I guess its just heat off the engine coming though. Could also be heat coming off of the heater core and some air is being forced in from outside.

 

[hyde]

I think that's one of the main reasons why Liberty cannot hold the A/C coolness inside, and it turns back into inferno the moment you turn of the A/C..
Same thing with Heat in the winter... What a drafty vehicle...

 

[K Dje Ryu]

My '05 doesn't do that.

 

[J-Thompson]

I think that's one of the main reasons why Liberty cannot hold the A/C coolness inside, and it turns back into inferno the moment you turn of the A/C..
Same thing with Heat in the winter... What a drafty vehicle...

my guess is that you have never been in a wrangler
hard or soft top
Good thing about the AC in my wrangler is that when the AC is on your feet stay nice and cool?

 

[JeepJeepster]

Its strange b/c mine doesnt always do it. Somedays I can feel the hot air coming through the vents one day and cant the next. Idk if it has something to do with the vacuum or what.

 

[Ry' N Jen]

Good day,

Ours does it sometimes and sometimes it doesn't! crazy.gif
I've been in some GM's, Ford's and VW's that also do it.

 

[hyde]

Its strange b/c mine doesnt always do it. Somedays I can feel the hot air coming through the vents one day and cant the next. Idk if it has something to do with the vacuum or what.

Yeah, that's right. It is not always. But when I touch there, it is almost always warm.

 

[SoDakJeep]

turn the knob to cold and it shouldnt be as warm.....haha at least thats how it is in mine.

 

[hyde]

Update, before it was only the defroster that was blowing cold with dial at 4, but now it is blowing cold in other positions as well. No matter if the engine is warm or not. I would drive half an hour at slow speed and not get any heat, but once I get to the highway and cruise at higher speeds with engine rev over 2k, it will start blowing heat and will be steady from there on. Sometimes it get very very hot. It looks like the I cannot adjust the heat dial from Very hot to Hot (thinner red strip).

So it is not as complicated now, simply put, driving slow no heat, driving fast heat...

 

[jeepgirl0385]

Could it be that in Chrysler's genius, they didn't let us choose between recirculate and not recirculate on anything other than AC, and so when we drive, the wind ends up being forced through the system, which would explain the level of air coming through when you are driving faster verses slower?

That's just my idea, because when I ride in my bf's metro and he has it on regular and the fan off, you still get air through the vents, and if it is on recirculate, then you don't.

That is one thing I hate about my Jeep is that you can't choose recirculate and the fact you can't turn the fan speed off without having to pass through AC. This is one area that a Metro was well designed, because it is easy to select. I think even the Dodge has a slightly different control that alleviates the fan speed zero issue.

 

[hyde]

Well, Jeep's A/C and Heater is poorly designed. Another problem I started having, I posted in another topic, now heater stopped working and it wouldn't blow heat unless I am driving fast.

 

[JeepJeepster]

Sounds like youve just got a vacuum leak somewhere hyedipin. Put the ****** in N and rev the engine alittle(around 2500 or so). If the heat starts working then thats probably the problem.

If that is the case, I would start by taking the radio surround off and checking for leaks in those hoses first.

 

[hyde]

I mentioned that before right, one day I took the dash apart and it hissed, I got scared shitless... I said "oh damn, i broke it"... but it was after that.. This has been almost a year now!!!!

 

[JeepJeepster]

Then you know where to start do ya!

 

[hyde]

But that was last year when I was swapping the radio. Such a long time.
How am I gonna check for a leak over there? Spit on it and wait for it to bubble!!?