# What’s this? Air vent edition

**URL:** <https://community.cartalk.com/t/what-s-this-air-vent-edition/133215>\
**Category:** Maintenance/Repairs\
**Created:** [January 24, 2019, 1:51am UTC](https://community.cartalk.com/t/what-s-this-air-vent-edition/133215 "2019-01-24T01:51:02Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![Lindseywelton30\_147397](https://avatars.discourse-cdn.com/v4/letter/l/4da419/32.png) [@Lindseywelton30\_147397](https://community.cartalk.com/u/Lindseywelton30_147397)\
**Post date:** [January 24, 2019, 1:51am UTC](https://community.cartalk.com/t/what-s-this-air-vent-edition/133215/1 "2019-01-24T01:51:02Z")

</div>

Mercedes M class, 2001. Was gifted this car with only 110,000 miles on it! But the vents keep shooting out this mess pictured. Face and defrost. Probably feet too. Appears to be some kind of foam substance. What is it? Should I be concerned?

Thank you!

 ![image](https://global.discourse-cdn.com/cartalk/original/2X/5/5593450e1754d76af03d325e356b353277fe9756.jpeg)

---

<div class="post-metadata">

**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\
**Post date:** [January 24, 2019, 1:55am UTC](https://community.cartalk.com/t/what-s-this-air-vent-edition/133215/2 "2019-01-24T01:55:33Z")

</div>

The various control doors in the vent system have foam applied to them so they don’t make noise when these doors change position.

What you’re seeing is this foam coming off the doors and blowing out the vents.

Tester

---

<div class="post-metadata">

**Author:** ![Purebred](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/purebred/32/46796_2.png) [@Purebred](https://community.cartalk.com/u/Purebred)\
**Post date:** [January 24, 2019, 1:56am UTC](https://community.cartalk.com/t/what-s-this-air-vent-edition/133215/3 "2019-01-24T01:56:31Z")

</div>

I suspect it is some sort of foam used at the various joints in the HVAC system. Me? I wouldn’t worry about it, though you may develope some rattles. But, I could be wrong.

---

<div class="post-metadata">

**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\
**Post date:** [January 24, 2019, 1:57am UTC](https://community.cartalk.com/t/what-s-this-air-vent-edition/133215/4 "2019-01-24T01:57:17Z")

</div>

The foam inside your evaporator housing is disintegrating and blowing in your face

nothing to be concerned about

just be glad the vehicle was free, because these vehicles were considered gravy trains for mechanics working at Benz dealers and independent shops specializing in that brand 😃

that money you didn’t have to spend buying the vehicle should be set aside for future big 💲 repairs

---

<div class="post-metadata">

**Author:** ![VOLVO-V70](https://avatars.discourse-cdn.com/v4/letter/v/8e8cbc/32.png) [@VOLVO-V70](https://community.cartalk.com/u/VOLVO-V70)\
**Post date:** [January 24, 2019, 3:09am UTC](https://community.cartalk.com/t/what-s-this-air-vent-edition/133215/5 "2019-01-24T03:09:59Z")

</div>

> [@Lindseywelton30\_147397](#):
>
> Appears to be some kind of foam substance

Foam it is. I had that with a used pickup truck and while annoying it is harmless and will stop eventually. I would wrap masking tape with the sticky side out around a popsicle stick and pull loose pieces out once in a while.

---

<div class="post-metadata">

**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\
**Post date:** [January 24, 2019, 4:30pm UTC](https://community.cartalk.com/t/what-s-this-air-vent-edition/133215/6 "2019-01-24T16:30:33Z")

</div>

18+ y.o. Merc.  
Just be glad bits of “stuff” aren’t dropping onto the road as you drive.