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Rain leak below dashboard -- hard to pinpoint

Had a cracked windshield replaced last spring. This winter have a bad leak during rainstorms. Definitely not coolant from heater core. The insulation on the firewall, under the carpeting, gets soaked. Took it back to the glass replacement company. They sprayed water all around. Since no water appears on the top of the dash, they said it’s plugged up drains at the air intakes, and bad insulation on the doors. I’ve cleaned all the leaves/compost away from air intake (removed wipers and cowling to do this), found one hole inside the door frame that was missing a rubber plug so fixed that. Latest rainstorm soaked the insides again.

Question is where a leak like this might be coming from, and what parts do I start replacing to find out? Have glass guys redo the windshield? Get new rubber weatherstrips for the door? The car is a 1996, 110k miles, spent its life outdoors in SF Bay Area, no visible rusted out parts. Never leaked at all here.

Would appreciate hearing if you have any experience with this. Thanks.

I have seen a lot of leaks where the heater/evaporator case meets the firewall on a lot of different cars. Don’t know if it’s gonna apply in your case or not.

Do you have a sunroof? If so the sunroof has drainage hoses…they get clogged up my sunroof drains are located in my front door jams. All you see is a little rubber flap looking thing (looks like something else I wont mention)…that flap has a slit in the end so if you were to squeez it horizontally it would open up…and let out funky water and debris… But if you have no sunroof…then…

Look around the cabin air filter. Sometimes a plastic shield will crack or not be installed correctly which can cause a leak.

Don’t use dish soap. Step 2: Use the bottle filled with a solution of car wash stuff and water, you want it to make suds after you squirt it around the windshield, sunroof or chrome or rain gutter (rare to have rain gutter). Close all windows and doors with the blower fan on maximum with outside air. If there is a leak, you will get sudsing. A bad leak will make you laugh at the quantity of suds.

I thought of something else…You A/C system has a box that houses the evaporator…this evap creates a lot of water via condensation…the water then leaks out of the car via a tube usually exiting the vehicle under the car on the passenger side… If the evap housing has a clogged or cracked tube the water that gets in the housing will find its way on to your rug…look into this… You will find its location on the net…the housing is or should be on the passenger side of the van… Make sure that drain hose is able to drain…

Pete – thanks for the reply. I’ve experienced coolant leaks in the cabin in past cars, and This is definitely not a coolant leak – it’s fresh water.

Thanks for the reply. No sunroof, however.

Thanks for the tip, I’ll check this out (cabin air filter)