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I’ve noticed multiple instances of condensation on the inside of my windshield when first getting into the car after it’s been raining (or I’ve been washing the car). A quick cycle of the defroster fixes things, but I’ve never experienced a car windshield having condensation develop when the car isn’t running. Has anyone else experienced this?
I definitely had that happen before in various cars. Moisture dragged in with wet cloth, shoes gets trapped and if the glass gets sufficiently cold, it condensates. Moisture likes to cling to dirt and oil, so especially on a new car the gassing out of the plastics causes a film on the inside of the windshield. Properly clean your inside of the windshield with a 50/50 alcohol/water solution. Don't use any commercial cleaners. They have all kinds of additional crap in it that just ends up on the glass. Also, leave the AC turned on at all times, so it dries the air. It will cycle on/off as needed. There's never really a need to manually turn off the AC in modern HVAC systems. It'll condition the air in the cabin as needed and removes moisture.
Last edited by superswiss; Oct 3, 2025 at 02:09 PM.
check for water leaks and or AC condensate drain clogged and or heater core leak.
You have excess moisture inside cabin which is really not normal as the car does have ability to "breath", so air is replaced when driving with fresh air.
I have the same issue. At times just washing the car if the interior is warm, condensation appears. Once I open the doors after drying and or turn the car on they clear. It never happens in my W238, nor my prior W213. I never turn the AC off. I think this is caused by the ventilation system, once you open the door, the fan turns on, even if you don't start the car so moist air is going into the car and the cooler windows from washing the car develop the condensation. I don't think anything is wrong.
I have the same issue. At times just washing the car if the interior is warm, condensation appears. Once I open the doors after drying and or turn the car on they clear. It never happens in my W238, nor my prior W213. I never turn the AC off. I think this is caused by the ventilation system, once you open the door, the fan turns on, even if you don't start the car so moist air is going into the car and the cooler windows from washing the car develop the condensation. I don't think anything is wrong.
Whenever I run my air conditioner, I shut it off 2 minutes prior to shutting the engine off.
Once the air conditioning is off, I run heat through the system, to avoid the possibility of any condensation forming inside the ducting after shutdown.
I have heard of mold and mildew forming and causing unpleasant odors from the hvac.
This gives the additional benefit of the air conditioner compressor not being on during start.
There probably is some system logic that prevents the compressor from being on during start, but I say, why risk it?
Also, since the Air conditioner comes on during defogging, I use the same process.
Agree, but I make sure my battery charger is connected while residual heat is operating.
I mainly use residual heat to cool down the turbos, while they are spinning down, but it can serve a dual purpose.
Agree, but I make sure my battery charger is connected while residual heat is operating.
I mainly use residual heat to cool down the turbos, while they are spinning down, but it can serve a dual purpose.
Whenever I run my air conditioner, I shut it off 2 minutes prior to shutting the engine off.
Once the air conditioning is off, I run heat through the system, to avoid the possibility of any condensation forming inside the ducting after shutdown.
I have heard of mold and mildew forming and causing unpleasant odors from the hvac.
This gives the additional benefit of the air conditioner compressor not being on during start.
There probably is some system logic that prevents the compressor from being on during start, but I say, why risk it?
Also, since the Air conditioner comes on during defogging, I use the same process.
is all of this really a thing? Feels like an awful lot of effort…..
is all of this really a thing? Feels like an awful lot of effort…..
It does seem like a bit much and seriously over thinking things. I just drive my car with the AC between 68° and 72°F all the time. Never had an issue in decades. 🤷
is all of this really a thing? Feels like an awful lot of effort…..
Ymmv.
I have definitely heard of it, more in moist, humid climes.
Every new ritual is an awful lot of effort, until it becomes a habit.
Of course everyone has to decide for themselves if the effort is worth it.
Ymmv.
I have definitely heard of it, more in moist, humid climes.
Every new ritual is an awful lot of effort, until it becomes a habit.
Of course everyone has to decide for themselves if the effort is worth it.
I lived in the Tampa Bay FL area for 20 years and now middle TN for 15 years and have never needed to do anything but leave the AC on auto and let the car do it's thing. Maybe with older cars that didn't have climate control, but not in any of my cars since at least 2000. Sometimes I'll get condensation on the windows, but it's only if it's very humid out and have never needed to run heat to dry out the vents. The AC compressor does that and I leave it on always to let the cars computer cycle it as needed. YMMV indeed.
I've never had condensation on the inside glass. I keep the A/C running in auto mode and set to 72°F. The notable exception is in the winter when the temps are in the low 70's and I open the windows. I've lived in Clearwater FL for 60 years.
I have noticed that before too . Turning on the A/C definitely repels the moisture away or opening the windows a bit . Using the windshield heat option is a useful too but I don't mostly prefer it because it automatically blows too much hot air into the cabin
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