I'm trying to figure out why the windshield and windows are always getting fogged up. This is happening during summer and winter and this is the first vehicle that this is happening with. I constantly have to run the defroster to keep it clear and I hate to blow the fuel economy by doing that. Is there a way to run the defroster without the AC on or where can water/ moisture be trapped that is causing the fogging?

 

I have the same problem ,hope someone has an answer.

 

It sounds like your evaporator drain in the firewall is clogged up, not netting the moisture out.
I always turn mine to vent or heat a few minutes before I get where I am going to let the evap. dry out so that it doesn't try to fog the windows when restarting. This is a benifit of having A/C.
Jimmy

 

I have a brand new F-150 no extended cab, same problem. I have to run defroster constantly.

 

Just put some rain-x on the inside of the windshield.

 

I tried something this morning, my windshield was again fogged up while running on "vent". I stopped for gas and used the sponge/squeegy thing on a stick to clean 1/2 of the inside of my windshield. I drove on to work and that part of the windshield stayed fog free while the other half was foggy. I know there's nothing magic in the solution they use, maybe the fogging is caused by dirty windows. My truck has only 2300 miles on it, so it must have been "factory dirt". Anyway, I'm going to clean all the rest of the glass inside and see if that stops all my fogging. Could it be that simple? lol

 

don't know if it is that simple or not...I use armor all glass cleaner...its is specifically designed for auto glass and to get all the residue and build up off the inside of auto glass...it works very well and much better than windex. if you find out that is what the problem is...I would recommend you use it on a regular basis.

 

I believe that the sun brings out chemicals in the dash and plastic interior pieces. These cling to the glass and this makes them much more apt to fog up. I have seen cars do this when they have cigarette smoke on the glass.
I smoke, but I always leave a window down to prevent this from happening. I have had no fogging problems with mine. I also try to keep a good coat of UV protectant on it like Son of a Gun protectant. This will help keep the sun from extracting the chemicals from the plastic.
Jimmy

 

Some cleaning and detailing solutions like armor all and some leather conditioners will actually cause your windows to fog up. An old trick that my father taught me was to use a newspaper and wipe down all of the interior windows. I know this sounds crazy, but it does work. Also, a good window cleaner like fisher _of_men recommended has seemed to help me out

Michael

 

when cars/trucks are delivered to a dealer from the factory, the windows are filthy inside and out. dirtry glass will fog up easier than clean glass. Some dressings and protectants will cause fogging, as well as smoking in a vehicle. I personally use "ZEP 40" non conductive surface cleaner, cold weather formula, and I clean my interior glass once a day, and if its not rainning, the exterior glass two or three times a day. MY windows don't fog up unless its wet out. but a few seconds of defrost air in any temp clears the light fog.

 

Don't worry too much about the fuel economy of the A/C either, (unless you have a 100 hp 4 cylinder) they've come a long way in recent years in compressor technology. I have 65k miles and I have had no difference in my mileage between winter and summer. None, and I keep a log and know enough to look at more than one tankful at a time when thinking of my average...

Sounds like either the moisture can't out of the evaporator and you have a moisture trap in a hose somewhere, something like that. One thing though - since we can't manually select inside air/outside air on these things, your outside air damper may not be working. You wan't outside air by the way, the people you see cruising around with all their windows fogged up don't have enough sense to turn off "recirc" and let some fresh air come though... You might check that air damper. Just a thought.