Another question/concern,
i have an 06 MC and the windshield always seems to fog on the inside no matter what the temp inside or out and it seems nothing I do, opening/closing windows, turning a/c on or off, defrost on or off seems to work! any tips?

 

When mine fogs up the defroster goes on and it does go away. Other than Rain-X No Fog I have nothing else to add.


Art

 

If the windshield 'fogs' especially when using the defroster and the only solution is to wipe away the residue (it does not evaporate), the most likely cause is a pinhole leak in the heater core causing a slight mist of antifreeze to accumulate on the glass. If the residue evaporates after a while, it could be caused by a plugged up or slow condensation drain at the a/c evaporator coil. Also, moisture buildup inside the car can often be caused by wet carpeting do do some external leak (sunroof, windows, etc).

Does the car smell musty? If so, this indicated moisture buildup. If it smells somewhat sweet, this can be caused by coolant leaking inside.

 

Running with the "Recirculating" button engaged will cause windows to fog up more easily. You didn't mention that, so perhaps that is where the issue is...

To defog windows quickly (on any car), adjust the temperature warmer, select the windshield setting, make sure outside/fresh air is selected (turn off recirculating/max setting), and turn on the A/C.

 

Newer cars also have "off gassing" of volatile organic componds from the plastics (and carpeting) in the interior. This makes the "normal" fogging (caused by moisture in the air condensing on a cold surface) worse.

Only real solution is to clean the windows thoroughly and frequently, and run that defroster when you need to.

Mine has the same problem - if I keep the windows clean it helps.

 

DixonL2 hit the nail on the head. Might want to add leather interior to the problem, as they can make the problem worse. Remember that is is "skin" and it does breathe, still.
Keep the windows clean, use a mixture of vinegar and water with newspaper of all things to clean right. Sounds crazy, but Italian Grandmothers can't be too crazy with all that damn glass and mirror to clean in an average household. Ha-ha-ha...

 

^^