30 year-old foam is no longer supple ('79 W123 ACCII temp sensor)

So today I finally pulled the front speakers out of my car. The
previous owners had blown them, and I was sick of them rattling so out
they came.

Driver's side was a snap, besides the fact that the screws are like
three inches from the windshield.

Passenger side, though. I noticed there's something else attached to
the speaker cover before I popped it off, but with no apparent way to
access it, I unscrewed the cover and pulled and tugged 'til it came
away. I couldn't get at the speaker connector from the top on this
side, so I dropped the kick panels (and I'm not entirely happy with the
way the firewall-side one went back in there when reassembled), and now
I noticed a rubber hose dangling. Oh, and a foam tube attached to the
hose. That foam tube which, as I touched it, crumbled more and more.

(Now, looking at the CD manual, I see I could have pulled the glovebox
to make this task easier. Alas, I did not.)

What I'm curious about, should I worry about getting this foam hose
replaced? What does that hose lead to? ...or is it just a
negative-pressure sort of thing to make sure the sensor doesn't heat up
in the sun?

For background, my ACC doesn't work. The servo cracked, and a few
months back I just jumpered it so I have all heat all the time. I
intend to fix it one day, although I'm still torn between the digital
replacement vs. the remanufactured units that we all know about here.
So, I'm not really sure if I even need to worry that this foam tube is
non-existant. What say you, oh majestic MBZ intelligentia?

thx,
-tom!

--

The tube is there so air can be drawn across the in-car sensor.

But since you need a servo and are not using the automatic temp feature, fix it when you fix the
system.


"Tom Plunket" <tomas (AT) fancy (DOT) org> wrote

So today I finally pulled the front speakers out of my car. The
previous owners had blown them, and I was sick of them rattling so out
they came.

Driver's side was a snap, besides the fact that the screws are like
three inches from the windshield.

Passenger side, though. I noticed there's something else attached to
the speaker cover before I popped it off, but with no apparent way to
access it, I unscrewed the cover and pulled and tugged 'til it came
away. I couldn't get at the speaker connector from the top on this
side, so I dropped the kick panels (and I'm not entirely happy with the
way the firewall-side one went back in there when reassembled), and now
I noticed a rubber hose dangling. Oh, and a foam tube attached to the
hose. That foam tube which, as I touched it, crumbled more and more.

(Now, looking at the CD manual, I see I could have pulled the glovebox
to make this task easier. Alas, I did not.)

What I'm curious about, should I worry about getting this foam hose
replaced? What does that hose lead to? ...or is it just a
negative-pressure sort of thing to make sure the sensor doesn't heat up
in the sun?

For background, my ACC doesn't work. The servo cracked, and a few
months back I just jumpered it so I have all heat all the time. I
intend to fix it one day, although I'm still torn between the digital
replacement vs. the remanufactured units that we all know about here.
So, I'm not really sure if I even need to worry that this foam tube is
non-existant. What say you, oh majestic MBZ intelligentia?

thx,
-tom!

--

The foam tube is the aspirator tube for the climate control - it draws
cabin air over the inside temperature sensor and exhausts same into the
blower intake. A piece of 5/8" drip irrigation tubing will serve as well
(but not as quietly).

Incidently, I converted my 116 to the www.unwired tools.com digital
climate control retrofit and now have a used OEM servo and used OEM
amplifier available to sell for their core values. Both are OEM original
(never rebuilt) and were working when I removed them. Both will fit your
123.
--
© 2007 T.G.Lambach. Publication in any form requires prior written
permission.

Karl wrote:

The tube is there so air can be drawn across the in-car sensor.

But since you need a servo and are not using the automatic temp feature,
fix it when you fix the system.

Sure. I was also wondering, though, where I might find foam tubing
that'd do the same sort of thing. Autohaus had nothing obvious.

thanks,
-tom!

--

On May 13, 12:49 am, "-->> T.G. Lambach <<--" <"T.G. Lambach at
NoHamorSpamcomcast.net"> wrote:

The foam tube is the aspirator tube for the climate control - it draws
cabin air over the inside temperature sensor and exhausts same into the
blower intake. A piece of 5/8" drip irrigation tubing will serve as well
(but not as quietly).

For a quieter version, use a piece of foam home hot water pipe
insulation that is sold at Home Depot or similar stores and made to go
around home copper water lines. Don't remember the exact size I used,
1/2-3/4, but it fits perfectly.

A while back, after having the AC worked on in my 300SD at a local
shop, I had noticed that the blower seemed to be making more noise at
the higher speed. Finally traced it to a vacuum hose like sucking
sound coming from the small air intake for the sensor in the center of
the dash. Then for a couple years I just put up with it, because for
the life of me, I couldn't figure out how this could be or what was
causing it, so I thought I must be imagining that it changed. Then,
one day while doing some work, I stumbled upon a piece of auto heater
hose that the shop had used to replace the foam piece of pipe. I
replaced it with the above solution and it made a substantial
difference in deadening the sucking sound. A hard rubber hose
transmits noise, while a foam type deadens it.

I think it's still not quite as quiet as original, but close. I
thought about gluing a piece of soft cloth to the inside of the
insulation pipe, which I think may cut it even more. Would be easy
to do, as the insulation is usually sold split when you buy it, with
an adhesive already on the joint, covered by a pull strip that you
remove to seal it.

trader4 wrote:

The foam tube is the aspirator tube for the climate control - it draws
cabin air over the inside temperature sensor and exhausts same into the
blower intake. A piece of 5/8" drip irrigation tubing will serve as well
(but not as quietly).

For a quieter version, use a piece of foam home hot water pipe
insulation that is sold at Home Depot or similar stores and made to go
around home copper water lines. Don't remember the exact size I used,
1/2-3/4, but it fits perfectly.

Ok, I wondered if this was state of the art for this sort of repair.

I thought I might look for something softer, more like the original
hose, but figured pipe insulation would work in a pinch.

thanks,
-tom!

--

On May 20, 12:22 am, Tom Plunket <t... (AT) fancy (DOT) org> wrote:

trader4 wrote:
The foam tube is the aspirator tube for the climate control - it draws
cabin air over the inside temperature sensor and exhausts same into the
blower intake. A piece of 5/8" drip irrigation tubing will serve as well
(but not as quietly).

For a quieter version, use a piece of foam home hot water pipe
insulation that is sold at Home Depot or similar stores and made to go
around home copper water lines. Don't remember the exact size I used,
1/2-3/4, but it fits perfectly.

Ok, I wondered if this was state of the art for this sort of repair.

I thought I might look for something softer, more like the original
hose, but figured pipe insulation would work in a pinch.

thanks,
-tom!

--

If you find something better, please let us know. I'd say the pipe
insulation may be about 75% as effective in deadening the sucking
sound as the original, but since I don;t have an original to compare
it too, no way to tell for sure. If you want to test how much
noise is still coming from the temp sensor intake, just block it with
your fingers. With a piece of plain rubber hose, most of the
objectionable AC noise is coming from that little sensor opening.