Recently I’ve been having an issue with the inside of my front windshield fogging up with a thick layer of condensation while I’m at school. School is only about 7 hours long and it’s winter which I know could be a contributor to the problem, but when I get to the parking lot, no one else’s car is like that. It’s also only the front windshield. No other windows or my back windshield is fogged and I know it is not an issue with the heater core because it doesn’t have the syrupy smell that people say it would have. I know it’s also most likely not from the snow that gets tracked into the carpets because then the rest of the windows would fog, wouldn’t they? I was wondering if anyone knew what is causing this and how I can make it stop.
Anything you can do to dry out the carpet and keep snow out will help. Be sure the HVAC is set on Fresh, not Recirculate. Some cars are more prone than others to this condensation, but do what you can do to keep the interior humidity low.
You may not think you have a leaky heater core, but I’ll bet you do.
I never heard it described as a syrupy smell, a slightly sweet smell.
With the engine cold, remove the Radiator cap. Smell that and then the carpet on the passenger side.
Are you sure you have 50/50 mix of antifreeze? If not it may not smell.
I’m asking because if the car was worked on in the last 6 months, it may have been filled with only water and no antifreeze.
Is your vent left on defrost when you park? Is the mode set to recirculate? Warm air rising up through the vents coupled with water inside (tracked in or vent mode left on recirculate) can result in condensation there. Another issue could be not clearing away snow over the vents right in front of the windshield, effectively blocking fresh air or making it excessively moist…
I had the exact symptoms that the OP is reporting, with my '86 Taurus.
No perceptible odor, but a constant fogging of the inside of the windshield.
It wasn’t until I was diagnosed with a serious respiratory illness that it finally dawned on me that I was inhaling aerosolized coolant, which takes a severe toll on one’s health.
It wasn’t exactly cheap to replace that heater core, but it was essential for my health and the health of my passengers.
I’m going to offer a second item to check. Make sure your A/C drain is clear. A puddle in the drip pan may contribute to this.