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2008 XC70 Vents blowing very wet humid air

Help, Advice, Owners' Discussion and DIY Tutorials on the current (third) generation Volvo V70 wagon and XC70 crossover, and second generation S80.

This is a forum for owners or prospective owners of the third generation V70, second generation S80, and its siblings built on the EUCD platform.
buddywa
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buddywa

2008 XC70 Vents blowing very wet humid air

Post by buddywa » Fri Aug 28, 2015 2:41 pm

I am a long time Volvo enthusiast and long time visitor to these forums however I have never posted.
I have recently been experiencing very wet and humid air coming from the vents on my 2008 Volvo XC70 when the car is blowing warm air. You don't notice the wet air when you have the AC on blowing cold air however I believe the water is just condensing in the vents instead. I searched the web everywhere and have found people with this problem but no real explanation.
This problem is most likely caused by a clogged drain inside of the evaporator/heater core box which is located inside of the dash. Another symptom of a clogged evaporator drain is the lack of water under the car after the AC has been running for awhile. You can easily check this by driving the car on a hot day with the AC on. Then park the car and check underneath for water dripping and a puddle of water forming. You should get a small puddle under the car. My car did not have this puddle at all.
It turns out the humid air in the vents was just the beginning of the problem, this can rust out your evaporator causing your AC not to work and more importantly it appears the water has made its way to the floor under the carpet which was soaking wet underneath. Upon searching this issue I found some people had clogged sun roof vents, I checked the vents by opening the sunroof and pouring water around the edge then watching and the water come out underneath the car.
Here is what the problem looked like when the vents were on:
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You can see water around the vents, this actually came from the humid air.
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Here is how I fixed the problem:
On the right hand side (passenger side in North America) I pulled off the bottom trim on the center console:
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Exposing the evaporator and heater core unit
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Pull back the carpet to expose the drain
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Put towels around and pulled off the drain hose. A lot of water came pouring out.
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Because water came pouring out of the upper drain hose, I know the clog is in the lower drain portion. So I purged the lower drain out with water in a medical syringe
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This took several flushes to get the water flowing and a lot of dirt came out of the lower drain hose
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I pulled back the carpet further and noticed everything was soaking wet
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These vents under the carpet and driver/passenger seat carry air to the rear of the vehicle, these were sitting in a pool of water
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I checked the driver's side and found the same problem, pools of water under the carpet. I then pulled the front carpet up as much as I could to let it air out. I did not pull the back carpet up because it is more difficult however I can tell there is water underneath.
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I continued to purge out the drain hole one last time.
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Check underneath the vehicle while purging out the line to make sure the water in going underneath as it should
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Re-attach the drain hose and dry up everything as much as possible
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I then ran a dehumidifier in the car (with the front carpets pulled back) for several days to remove all of the moisture. I ended up renting a industrial dehumidifier to speed up the process (no picture).
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I hope this helps someone and thank you to everyone for posting things which have helped me in the past!



humbertoflores63
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humbertoflores63

Re: 2008 XC70 Vents blowing very wet humid air

Post by humbertoflores63 » Thu Dec 31, 2015 4:36 pm

I am not sure if this applies to your car, but the older models 850 and S/70's have a large drain that gets plug and water will work its way into the cabin. The drain drains all the water that gets collected in the cowl where the wiper motor sits. It has a slope towards the passenger side and the drain in next to the cabin filter check this on your car.

At some point you also need to clean the 2 rear drains from the sunroof. The tube drains are behind the wheel wells and blow the stuff backwards with an air hose!



okuley
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okuley

Re: 2008 XC70 Vents blowing very wet humid air

Post by okuley » Tue Aug 09, 2016 11:55 am

I would really love to see the photos for this posting. I am having this exact problem right now!! For some reason the photos are not visible?!



buddywa
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Year and Model: XC70 2008
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buddywa

Re: 2008 XC70 Vents blowing very wet humid air

Post by buddywa » Wed May 30, 2018 6:22 pm

I have fixed the broken links to the images.
Don't forget to check the sunroof drain too. There is a drain hose on the right and left A pillars next to the windshield. If you open the sunroof and pour water on the right and left side (there is a water catch basin), the water should run out behind the wheel wells.

Also an update on this repair (and also later my clogged sunroof drain repair):
YOU WILL LIKELY NEED TO REMOVE THE ENTIER CARPET, SEATS AND CENTRE CONSOLE TO TRUELY REPAIR THIS!
I put that in caps, because don't use a dehumidifier like I depicted. That did not work after.
If you have the amount of water seen in my pictures (or more) you must remove the carpet.
To do this; remove the front and rear seats, pull up the rear carper first, and then you will need to remove the centre console to get the front carpet out.
The carpet has about 2 inches of foam under it, it will drip water for a week after you take it out of the car and bring it into your house to dry. If you do not do this, your floor will rust and wires will corrode leading to a very dangerous scenario.
The Volvo owners manual says do not operate your car if the carpet is saturated. This could cause a short circuit trigger the airbag module.
If you don't do anything else, remove the carpet and dry everything!

Good luck!



rcannon
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rcannon

Re: 2008 XC70 Vents blowing very wet humid air

Post by rcannon » Sat Jun 16, 2018 4:30 pm

How did the debris get in there? Should be caught by the cabin filter.



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