What could cause a lot of condensation inside van, to the point where the carpet smells like mildew? Water droplets under seats on the metal. moisture on the tv screen

I had a work van with excess moisture problem, had to put it in the garage a couple days with dehumidifier, after that I separated a large bag of charcoal into 4 smaller open mesh containers in different areas inside van, made sure to keep floor mats dry as possible, opened windows to ventilate, all this really helped enough to say 90% better. But there is still a lot of metal going through the heat and cooling process in the winters. below is a good link to help answer your question, press the helpful button.

How to stop condensation in your car

Ac drain line plugged or broken leaking on carpet or heater core is leaking

Just a thought if you want to deal with the moisture there is a chemical dehumidifier that they use in trailers... it is cheap and the crystals last for a few months, just need to empty it once in a while. But the problem is probably as mentioned above, the drain for the ac is plugged or needs to be treated with deodorizer, also check to make sure the heat isn't set to recycle... keeps bringing the same air around without refreshing it.. moisture will only keep building because Everytime you breath it is more trapped moisture in the cars air.

LPfaff, gave you the only answer you need, metal inside van, cools and heats causing excess moisture. In his answer to you, he tells you how to take care of the problem, try the advice. It has worked for countless others.

If you touch the carpet, is it wet everywhere or can you determine a specific area? Which area?
How long has thing been happening?
Does it only happen when it's raining?
How about in the summer when there is no rain?
Which make/model/year van?
When you run the air conditioner, does it drip out side, under the van?
Does the air conditioner give off a musty odor?
When you run the heater, it is warm?
Does the water have a smell?
Are there holes in the floor board under the carpet?
Is water pooling under the carpet?
Is the carpet soaked?

The water either has to come from a source that's a continuing problem or form inside the car when and where hot meets cold...basically like rain.

I suggest using a wet/dry vac to get as much water as you can off the carpet and wipe everything down so its as dry as possible and leave the car overnight without driving it. Is it wet in the morning?

If it gets wet during the day then I suspect it may be a leaking heater hose or related to the air conditioning.

In cold weather, There isn't condensation from the HVAC system when running and it is sealed. The A/C doesn't run enough to cause it, it only cycles every once in a while for the defroster. The heater core doesn't create it, it drys out the air. So you like me have a small heater core leak. You want see the leak because it evaporates, causing the windows to fog up. I'm waiting till warm weather to replace it, unless it blows out. I have a 99 Dodge caravan. And yes, we both have to pull the entire dash out to replace the heater core. Using radiator stop leak will plug the leak and most of the heater core.

Definitely plugged condensate drain line lines run from evaporator coil enclosure to line going
Outside bottom of vehicle. Lines break sometimes but this is rare. As corrosion and rust come off coils they plug lines. You can open enclosure clean and flush inside enclosure and cool with special cleaner.

Check rubber gaskets on doors that seal out sound and moisture when doors are closed. Also check for leaks in condenser for air conditioning, or leak in fire wall or openings with rubber plugs missing, in floor too!
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Check drain plugs from underneath the vehicle. They're usually located in the floor pans. Never leave wet mats in the vehicle either.

I suggest its vapourisation,.any time u park ur van make sure that you open the doors nd whine all the glass down,,, to allow ventilation inside the bus..,30-45 minutes is enough...

If its just condensation you cant do much you can clean your windows because dirt will condensate more only other thing i could suggest is put a dish of cat litter or floor dry under a seat or something