If an oily film is left on the windshield, suspect a leaking heater core. Normally antifreeze smells sweet, not like what you described. To be sure, check the coolant level in the overflow reservoir. If it is not dropping and you haven't had to add coolant, suspect a different, more likely problem.
There is a drain pan under the ac evaporator to catch condensation when the ac runs, including in the defrost mode. Sometimes the drain tube becomes plugged, and the standing water can start to smell. Check the rubber drain tube on the passenger side firewall under the hood. It has a 90 degree bend molded in and is about 4" long. You can squeeze it to dislodge debris. If water comes pouring out, your problem is solved. If nothing comes out, there is a wire clamp ring you can squeeze to allow you to pull the hose off. Then, slowly stick a pencil in the tube to remove any blockage.
The Chrysler dealer's parts department has a can of odor neutralizer for ac systems too. That's not a cure for a problem. Its a remedy if the smell lingers after the problem is solved.
March, 4, 2010 AT 4:34 PM
There is was no blockage in the tube and the coolant level was fine?
March, 4, 2010 AT 5:07 PM
Hmmm. The only other thing I can think of is if there is snow or water over the fresh air intake, but that is not unusual.
You might try to observe if the smell occurs only when the fan is running at certain speeds. Worn brushes in the motor can arc more than normal making a hard-to-describe burning smell. Tight bearings in the motor will cause it to draw higher than normal current through the motor speed control resistor block. That block is bypassed in the highest speed. An overheated resistor can cause a smell, but it is more likely to blow a built-in thermal fuse. At that point, the fan will only run on the fastest setting. That resistor will not cause windshield fogging. I suppose arcing motor brushes could, but that would be odd.
Does the fogging occur all the time?
March, 4, 2010 AT 5:55 PM
Yes and sometimes a mist comes out?
March, 4, 2010 AT 5:57 PM
Out of the vents.
March, 5, 2010 AT 10:01 PM
So, where you able to determine if the fan speed has anything to do with the misting? Any other observations that could be a clue?