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!
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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.

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Karl wrote:

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

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.
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trader4 wrote:

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!
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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.
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coo

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