91 Maxima --> windshield keeps fogging on the inside all the time now (fresh air, defrost, ac, etc). This time, while cleaning it, I used a razor blade. Discovered black film over the inside of windshield, similar to oil. Anyone got any suggestions on what this is (could it indeed be oil) and where it might be coming into the system? Any help would be appreciated. Thanks,

 

That's what happened to me when my heater core went... If it IS the core, I hope either A) You're mechanically inclined or B) You have friends that are... It's in the books as a 12 hour job, and believe me, it WILL take that long to do it, and you'll have to discharge your A/C to remove it.

 

Hmmm. That's at least decent to hear that your heater core resulted in black crud on the windshield. Thanks for that.

Now, I have to do some research and find out if there's any way to test it or not...I doubt there is.

I've changed many a heater core in many a car...Some are easy, some aren't. Sounds like this falls into the "some just suck a$$" category...

 

Ohhh ya... And you wanna know the worst part? THe only reason you need to discharge the AC is to move the hose about 1/2" out of the way so you can pull the core out... Almost everything is dissasembled from inside the compartment, very minimal stuff under the hood. But you have to pull the entire inside chassis for the center console, which means dissasembling the entire dashboard, gauges, HCU, stereo, and taking out the plastic AND metal chassis, airbag, etc.... You'll end up with a LOT of wires left over.
As for testing it, I'm not sure, the core is located RIGHT behind the glove compartment, but it's almost impossible to see anything unless it's really bad.
When my brother finally got to the core itself, he called me up (I left it at his house and he did the last parts in his free time) and you know what caused it? A penny fell down my vents and caused it to corrode... He spent a good hour cleaning all the rusty watermarks from everything in there, which you couldn't even see until you got down into it (When he does work on a car, he does it right, I didn't even know he cleaned it up until last week)
Uhmmm, good luck?

 

stop smoking pot in your car. that is my problem it will mess up your winshield when it rains.. damb resin

 

Ya, I wish that were the problem...Not such an easy "fix"

 

Pickle juice breaks it right up... Just make sure you don't get any on the fabric, Febreeze doesn't work well getting the smell out of carseats...

 

Technically, picke juice is vinegar and that is an effective window cleaner. Another thing you might want to try is rubbing alcohol.