windshield fogs and defroster makes it worse, bad scent from vents
 

When my windshield fogs up I use my defroster and it gets worse, bad scent coming from defroster, but it doesnt smell like coolant, and it gets a rainbow colored haze. This happens mostly when driving. When sitting and idling it clears up VERY VERY slowly. When I start driving again, it immediately fogs up again to the point I can't see. The air is hot that comes out of the defrosters and my vents. What things could be causing this so that I can check. The car is a S4 NA with a mild street port. No other mods on the car. Please help!

if you get a "film " on the windshield,and it feels a little greasy,most likely it's the heater core..sounds like a heater core leak..had one in my "other car",and it would leave crap on the windshield..that's my take on it..have you checked coolant?.pressure test the cooling system..look for signs of leaking especially around the heater core and inside the car(floor)..another thing..if your car was stored or was outside for awhile and dormant..you just may have "critter litter" in your vents..you know animals!..anyways that's all I can give you ..

wipe the glass with your finger and tell me what it tastes like - seriously

Also check for oil leaking on the manifold. When my OMP was still in and leaking it would drip back there and stink up my car and coat the windows with rainbow haze after a while like you described.

As for general fog, My GXL used to fog up something terrible in the cold/wet winter, heres what worked for me.

1. Thoroughly clean inside of windows with glass cleaner.
2. Use clean towell to dry off completely.
3. Apply rain-x anti fog or whatever you got, let that dry.
4. Run defrost at full hotest setting and make sure you have recirculation pressed.
(^^ This makes it worse for a while but the idea is to evaporate the extra moisture in the car.)
5. Keep windows shut whenever possible to avoid dampening interior further.

Ive found even a little rain in the car causes lots of fog for a bit

quit trying to kill the forum members..... seriously.

Can we tell him to have his dog taste it? If the dog doesn't want to stop licking the windshield its the heater core. You will need a new core and a new dog.

We have a couple of shade tree mechanics here... that is a old shade tree mechanic trick (that of course I would never ever ever suggest or try- I know what happens when you drink glycol)

in all fairness though - this is an effective method of determination.

Im not telling him to crack a 4liter jug of antifrezze and start chugging.

touching you finger with glycol rsidue to your tounge is certainly not the MOST health consicous thing to do but it is certainly not going to cause blindness or sickness in any way, otherwise I wouldn't be typing right now.

besides, I don't see any other really really effective suggestions posted thus far and its not like he HAS to take my advice anyways...if everyone on here took everyones advice we would have a nation full of people who are afriad to change their oil from mineral to synthetic..........wait maybe thats a bad example - LOL

edit: but Im sorry if this was enterprueted as a harmful suggestion and will use better discretion in the future - I just think its a quick and easy way to check and see if there is a hole in the heater core - sorry

its not all that hard to figure out, if there is a slimy residue on the windshield that is coming from the defroster vents you can pretty much guarantee the heater core is shot.

No less deadly than telling someone to taste the oil and if it burns your tounge there is too much gas in it and you need to change the oil

No that is a great example... but what you are missing is that half the newbies do take anyone and everyone's advice that is given within the first 24 hours of their post.

the sweet smell is also a good giveaway for a leaky heater core.

If the windshield fogs on fresh air, and not on reciculate, and has an earthy smell, you may have organic material built up in the cowl, (leaves, pine needles, etc.).

Some people are jumping into conclusions here...
I've only seen one bad heater core so far.
I've seen TONS of bad heater hose connections to the heater core at the firewall.
The coolant tends to seep back into the interior.
That stuff slowly turns to vapor and rises...guess where is right above?
The windshield.


-Ted

some problems are also area specific, just because you haven't seen it happen often doesn't mean it isn't common in other areas.