Have a question concerning the vacuum hose arrangement as it relates to the heating-air conditioning function. I am looking at the "Vacuum function diagram" (63-604) from the cd for a 76 450 sel. In this maze of tubing is a point that they call "Specified leak poimt" It is item #38 on this drawing. On my car the tubing at this point is plugged with something. My question is, is this supposed to be plugged or should the end of the tubing be open. The term specified leak point seems to be saying the tube should be open or am I missing the point? If someone knowns I would appreciate any reply. Milt.

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Milterino
76 450 S.E.L.

I have seen vacuum lines with orifices designed to control reaction speed to some components and for some reason, used to have a few in the garage.

If it is inline to something, it would control (delay) initial movement. If in an open line, it would control (delay) the relaxation of the item.

The hole may be too small to see or it might be plugged. Blow through it into some water and look for bubbles or Mity-vac it and check for leakage.

Michael

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Usta haves '69 250/8, '76 280C, 1971 250C 114.023, 1976 450SEL 116.033
Current have, 1983 300SD 126.120

leak points should be unplugged.
under dash of my 6.9 I found a coil of green vac line unplugged. it looks unintended, but it is supposed to be open.

this may be what you are seeing

Well thanks for the replies. I will unplug it and try to figure out if it makes a difference. I am trying to fathom what will make the servo heat valve work. Got one from the jumkyard that wasn't cracked but even that does not work. Took the old one apart and it was a complete mess in side from corrosion and gunk. This person who designed this heating system has to be first in line for the booby prize of 1976. Anyway thanks again, Milt.

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Milterino
76 450 S.E.L.

O.K. I have inspected the coil of what I thought was tubing but it turns out it is a coil of insulated wire with one end open to the athmosphere and the other inserted into a tee in the vacuum line. All I can figure is that this is what they figure will leak the desired amount of air? Milt.

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Milterino
76 450 S.E.L.

Just a note to clarify the situation. The wire which comprised the coil is stranded so I assume there is room for air to travel in the strand and provide the leak point. Milt.

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Milterino
76 450 S.E.L.

http://imperialclub.com/Repair/Lit/Master/281/cover.htm

blame Chrysler

the system pre-dates 1976

link is to a manual and it doesn't go into troubleshooting, but there is enough theory there to perhaps suggest why your heater valve is not behaving as it should.

there are many things happening in servoland.

My ACC worked perfectly for about a year: the fan blower would speed up and slow down and the flaps would open and close as designed. It is pretty good when it works as intended. Right now a tire gauge is propping open my center vents. I will get around to it, but a new car is distracting me right now.

If you do get your heater valve where you want it, you can unplug the electrical connectors on the servo. Leave the vac. tubes alone. It won't be automatic, but you will have the heat or ac you need.

Oxy: Thanks, that's an interesting site which sure puts me ahead of where I was. Couldn't print it but put it in my favorites where I can reference as needed. They talk about the manual system which must be pre 76 so that might be a possible route if I could find one in the junkyard. Milt.

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Milterino
76 450 S.E.L.