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WOW - what a major production to fix and such a common fault looks like 100% will have this.

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With the coming of heating season, i have been using my heater quite a bit.

On the one hand, I am happily remembering how good the heater is especially as compared to my BMW.

On the other, I am now getting bathed in black foam bits. That was common before. New this year, however, is CHUNKS of black foam. They sometimes come through the vents, but more commonly, they are strained from the airflow by the vent grills.
The driver's side dash vent seems to be the worst.

I spend several minutes with a little hook and needle nose pliers. I retrieved much of the foam blocking the vent. At least the hissing has stopped.

So - is there a brilliant solution to this problem? The foam must be coming from somewhere and now there is a fair amount coming out.

Is there a suggested way to remove the foam from the vents? Fishing it out works, but is a nuisance.

When will this stop? I want to wear white shirts again.



Edited 1 time(s). Last edit at 11/27/2019 09:22AM by JMstamford,ct. (view changes)
The infamous black foam comes from the air dams in the HVAC system.
After 10 or so years, due to heat, humidity and bad sourcing, the foam in the dams stats to deteriorate and just crumbles.
There are various solutions:
1.- Replace the complete HVAC unit at exten$ive co$t.
2.- DIY fix to repair the air dam foam. Not easy, not quick. Most give up.
3.- Don't wear white winking smiley
After some months, it will go away, although there won't be much control over the air diverting.
To accelerate the cleanup, close all air vents but one. Use a towel to close off the windshield vents.
Put a vacuum cleaner hose right onto the one open vent and turn on the fan full blast.
Use pick to help clear vent. Once that vent is cleaned, close it and open the next vent. Repeat until all vents are clean.
You may have to repeat the above procedure several times before all is cleared.
Happy Boxstering,
Pedro

Pedro Bonilla 1998 Boxster 986 - 293,000+ miles: http://www.PedrosGarage.com
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna
If you live in a place where you drive the car in colder weather, you need a functioning heater. I had experienced the black/grey foam storms, and the lack of real heat. Like Pedro says, the issue comes from the mixer door that is meant to control the blend of heated and unheated air. The door itself has large holes - for reasons not entirely clear to me - that are covered by the offending foam. Time and heat cause the glue and foam to deteriorate, and the foam to exit the vents. The heated vs. unheated air can't be separated, so you end up not only with the messy foam problem but a lack of real heated air (it'll be lukewarm, at best).

There are two DIY approaches - one involves going in through the heater from the top (under the front cowl), and the other involves accessing the mixer door through the inside center vents. I performed the former (I don't think anyone had come up with the latter approach by the time I addressed the issue four years ago). As Pedro says, it was not easy and not quick - but I was able to do it and I am not the world's foremost DIY'er. Most of the work is just removing things to get at the mixer door (an argument for why the latter approach may be easier, but it does involve some cutting, IIRC). From there, it's just a matter of buying some 3M insulating foam at your local Home Depot or hardware store, re-foaming the door, and putting everything back together.

If you search "blowing foam" or similar on 986forum.com, you'll find a lot of good info and step by step write ups on it. Again, if you don't need good heat (maybe you put the car into 6 month hibernation - sounds like you're in CT) I'd just use the vacuum method. But you'd be surprised at how much foam keeps coming out. It's like you've struck the never ending mother load of great foam deep in the heart of the Boxster!

Gary 2003 Boxster Base - Midnight Blue Metallic, Savanna Beige, Metropol Blue


Pedro Bonilla 1998 Boxster 986 - 293,000+ miles: http://www.PedrosGarage.com
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna
And what a questionable design in the first place.

There must have been a reason for the holes in the flap. Please tell me it was not to save weight.



Edited 1 time(s). Last edit at 12/02/2019 11:25AM by JMstamford,ct. (view changes)
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