Pools of Water coming from rear ac floor vent

stowers561 · 04-22-2021, 02:22 PM

So there was a pool of water in my backseat so I searched the forums and saw a lot of discussion about the vapor barrier in the doorcards, however I checked and mine were fine. I cleaned up and dried all the water the best I could. Next morning the floor still looked fine so I drove to the gas station. When I got there the pool of water was back. It looks like it’s coming from the ac vent on the floor under the drivers seat. Any idea how to fix this or where the issue is ?

stowers561 · 04-25-2021, 08:36 PM

bump, still looking for any help on this. I dried it all up and it remained dry for a few days, washed the car today and its back. I feel like its coming from the cowl under the windshield where the drains are located. Does anyone know where they are supposed to exit?

E92_William · 04-25-2021, 08:45 PM

I thought the drains on the cowl are supposed to exit right behind the fender and door area. People never clean that so it could very well be clogged from previous owners.

stowers561 · 04-26-2021, 06:51 PM

Yeah thats my understanding as well, I'm out of ideas maybe clogged AC drain but when I stop driving it looks like its draining fine under the car. I'm open to any ideas

E92_William · 04-26-2021, 08:26 PM

Pour water directly into the drain with it being dry outside to see what happens

Efthreeoh · 04-27-2021, 09:18 AM

I'd also check the sunroof drains just to eliminate them. The only thing I could see is if the cabin air filter is not fitted correctly and water is getting into the HVAC vents, overwhelming the AC condensate drain and exiting out the under seat heat vent.

houbmw · 04-27-2021, 09:31 AM

Did you ever replace your front windshield? The cowl that goes needs to be properly places. Also, there is a compartment under the cowl that CAN collect debris and clog those drains. That water is coming from the front and following your ducts inside to your rear passanger compartment first

jarsdad1 · 04-28-2021, 02:24 PM

Try this:
1) dry the floor thoroughly.
2) hose off the car for a bit. Focus on sunroof and driver side rear window.
3) after a bit check the driver side seat belt for moisture.
4) open ds rear door and check for water in sill and door. Check the carpet for moisture.

If seat belt is damp, probably SR drains; if carpet is wet, probably vapor barrier.

04-22-2021, 02:22 PM	#1
stowers561 Registered 2 Rep 4 Posts Drives: 2010 328i Join Date: Jan 2021 Location: Palm Beach Gardens, FL iTrader: (0)	Pools of Water coming from rear ac floor vent So there was a pool of water in my backseat so I searched the forums and saw a lot of discussion about the vapor barrier in the doorcards, however I checked and mine were fine. I cleaned up and dried all the water the best I could. Next morning the floor still looked fine so I drove to the gas station. When I got there the pool of water was back. It looks like it’s coming from the ac vent on the floor under the drivers seat. Any idea how to fix this or where the issue is ? Attached Images
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04-25-2021, 08:36 PM	#2
stowers561 Registered 2 Rep 4 Posts Drives: 2010 328i Join Date: Jan 2021 Location: Palm Beach Gardens, FL iTrader: (0)	bump, still looking for any help on this. I dried it all up and it remained dry for a few days, washed the car today and its back. I feel like its coming from the cowl under the windshield where the drains are located. Does anyone know where they are supposed to exit?
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04-25-2021, 08:45 PM	#3
E92_William Captain 1306 Rep 852 Posts Drives: 2008 BMW 328xi Join Date: Apr 2021 Location: South Florida iTrader: (0)	I thought the drains on the cowl are supposed to exit right behind the fender and door area. People never clean that so it could very well be clogged from previous owners. __________________ Airplane Mechanic BMW Masochist
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04-26-2021, 06:51 PM	#4
stowers561 Registered 2 Rep 4 Posts Drives: 2010 328i Join Date: Jan 2021 Location: Palm Beach Gardens, FL iTrader: (0)	Yeah thats my understanding as well, I'm out of ideas maybe clogged AC drain but when I stop driving it looks like its draining fine under the car. I'm open to any ideas
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04-26-2021, 08:26 PM	#5
E92_William Captain 1306 Rep 852 Posts Drives: 2008 BMW 328xi Join Date: Apr 2021 Location: South Florida iTrader: (0)	Pour water directly into the drain with it being dry outside to see what happens __________________ Airplane Mechanic BMW Masochist
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04-27-2021, 09:18 AM	#6
Efthreeoh General 17303 Rep 18,727 Posts Drives: The E90 + Z4 Coupe & Z3 R'ster Join Date: May 2012 Location: Virginia iTrader: (0)	I'd also check the sunroof drains just to eliminate them. The only thing I could see is if the cabin air filter is not fitted correctly and water is getting into the HVAC vents, overwhelming the AC condensate drain and exiting out the under seat heat vent.
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04-27-2021, 09:31 AM	#7
houbmw First Lieutenant 66 Rep 309 Posts Drives: 2007 530i Sport with SMG Join Date: Jul 2010 Location: Davie, Florida iTrader: (0)	Did you ever replace your front windshield? The cowl that goes needs to be properly places. Also, there is a compartment under the cowl that CAN collect debris and clog those drains. That water is coming from the front and following your ducts inside to your rear passanger compartment first
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04-28-2021, 02:24 PM	#8
jarsdad1 Private First Class 55 Rep 172 Posts Drives: 2011 535i, 2015 X1 3.5 Join Date: Oct 2016 Location: Philadelphia, PA iTrader: (0)	Try this: 1) dry the floor thoroughly. 2) hose off the car for a bit. Focus on sunroof and driver side rear window. 3) after a bit check the driver side seat belt for moisture. 4) open ds rear door and check for water in sill and door. Check the carpet for moisture. If seat belt is damp, probably SR drains; if carpet is wet, probably vapor barrier.
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