I have a 94 camry with a totally mysterious foggy windshield issue. I’ve taken it to a good mechanic who has looked into it on a couple occasions, to no avail. It seems to be worse in the spring/summer, perhaps – no matter how often I clean the windshield, it’s VERY prone to streakiness. It’s like there’s a substance, maybe coming from my AC, that gets on there? I’ve never experienced this with another car. If anyone has any thoughts, I’d appreciate it. Thanks!
Probable causes (in order from cheapest to most expensive solutions):
Make sure that you don’t have the HVAC system set to “recirculate”. Recirculating the inside air will tend to cause a build-up of moisture in the interior. Also be sure that you are using the A/C and not just the vent function on damp days.
If you are in the habit of using Armorall or something similar on the dashboard, clean it off and see if that stops the build-up of whatever is coating the windshield.
Check your radiator to see if you are low on coolant. The symptoms that you describe can also be indicative of a bad heater core, meaning that coolant could be leaking from the heater core and entering the passenger compartment. If this is the case, the coating on the inside of the windshield will feel somewhat oily. If you do need to replace the heater core, bear in mind that the repair cost may exceed the book value of your car. The heater core is relatively cheap, but the labor to replace it can be obscenely expensive.
Great list from VDC, but I will add the possibility of a blocked drain in the AC unit.
A leaky heater core is usaually accompanied by a sickly smell of sour currie! Plus the fog over the defroster duct. As VC said, we hope it’s your recirc setting or a plugged A/C drain.
Many years ago in Saudi Arabia I had to show my driver during one of the rare rain storms that the Buick LeSabre has a defroster setting. After reaching over an putting the fan on high with the defrost setting I qualified as a miracle worker.
Check the heater core like others have suggested. What does happen on all cars is fumes from the chemicals used to make the instrument panel gasses out and causes a film on the windshield.
“What does happen on all cars is fumes from the chemicals used to make the instrument panel gasses out and causes a film on the windshield.”
That is true, but out-gassing usually stops after a few years. On a 14 year old car, I think that out-gassing of plasticizers can be ruled out.