Just say NO to pods. I've been into pods for only 3 weeks and it has only led to dizzyness, confusion, muscle aches, insomnia and now wet feet...

I fear that they may lead to stronger stuff like "IP"'s and "Bowden Cables".

It may be too late for me...

The ACC II system in the W123 has started acting up.

When i turn it to auto lo, auto hi, or bi-level, the fan comes on but the compressor never does.

The compressor works on defrost.

I just found the 10 pin test port under the dash, never knew that was there. I tested the in car temp sensor, ambient temp sensor, and the temp wheel. Everything was fine however with the temp wheel at 75 degrees i had 806ohms, the oracle says i should has 900 ohms, so i adjusted the temp wheel to read properly.

The servo runs when i put power to pins 4 and 5. But the servo will not run when i turn the temp wheel.

I swapped in anther amp which was a known good unit, same problem, servo wont run.

Hey Doktor Bert - Do you have any knowledge on the vacuum levels of the Climate Control system (measured from engine compartment) on different heat control settings?

I have a problem in my Climate Control system that is causing engine shutdown issues. I would like to use my hand-pump vac gauge to help diagnose parts of the system which are causing the leak - or at least what i think is a leak. So far i have located 2 failed (leaking) points and wonder if there are more.

Here is the link and snippet of my question from that post regarding vacuum
http://www.peachparts.com/shopforum/diesel-discussion/310231-remove-ccu-116-300sd-engine-shutdown-issue.html

Tested system with vacuum gauge inline:
(edit) vacuum gauge inline at firewall inside engine compartment, green/black vac line (edit)
Off = 7"
Auto Lo = 7"
Auto High = 7"
Bi Level = 20"
DEF = 20"

Note: Item #38 shows "Specified leak point" so that might reflect in the measured results???

Have you pulled a vacuum on your shut off diaphragm directly to see if it has a leak?

Kerry - Yes i have, shutoff will hold vacuum. I was shooting for vacuum levels when different parts of the circuits (vacuum paths) in specific operating modes, hoping to locate where additional failed vacuum line connectors (soft black rubber sections) might be. I have tested all the engine compartment vacuum lines for leaks and ended up having to dive into the Climate Control system. I have not checked out the Servo vac lines as i consider that part of the CC system.

Looks like i need to pull off the mufti-vacuum line snap-on block (see photo) from the rear of CCU to assist in flushing out oil from each section the best i can with brake cleaner and compressed air.

I have current pictures and shop drawings to assist in dismantling sections to flush. Anyone go down this road before with suggestions, please let me know.

So is the oil from a previous failure or is one of the pump diaphragms leaking?

Good question. How would i find out? I have not replaced or rebuilt either type of vacuum pump. Would i remove the top screws and notice what exactly? There is more oil in the lower sections (back of CCU, Fresh Air actuator) than in the main vacuum supply tube and the branch sections like the shutoff. I have attached the repair kit listed from Fastlane. Given the cost of the repair kit i don't see a reason to fix rather than replace.

Since current pump is pulling good vacuum, I am focusing on the CC system. I plan to install an in-line clear filter, or filters, to monitor oil in vacuum system.

I welcome any insight or other ideas you may have.

I'd suspect the shut off diaphragm. It can hold enough vacuum to work but still be leaking oil. I think you have an 80SD don't you? If so, you have the double diaphragm pump so the kit you linked is not the right one.
Pull a vacuum on the shut off with a clear hose on the Mity Vac and see if you suck any oil into the hose after the vacuum sits on it for a few minutes.

Kerry - Yes, 80SD but with new style pump as pictured with only one vacuum outlet.

I will test as you suggested with pulling vacuum on shutoff with clear tube and recheck after some period of time.

Kerry - No leaks (oil) from shutoff. Have downloaded shop procedures for testing vacuum lines and CCU push button operation. The CCU is/was leaking oil around the perimeter of seam between main body and rear connection plate where vacuum lines and electrical connection - see photo with red arrows. Clear plastic tube is attached to CCU at port #6 (main vacuum feed from pump) for running tests.

Update - Think if have found the vac circuit leak in question.

I don't see (*edit* OK, found them :D) the check valves labeled on the drawing (#'s 82, 83, or 34) anywhere behind CCU or under dash???

I started to go through the CCU 4 main vacuum line circuits or routes (device #2, ports 1 - 4 & 6, 5 & 7 are not used) relating to the drawing below. I disconnected each line where possible, capped both ends and ran my vacuum test again. One line (purple) in my initial cleaning was too tight to reach so i snipped it and installed black rubber splice to repair after black flushing (green circle with red slash). This allowed for easy testing (disconnect and capping) for that segment. After capping both segments, starting engine and running through tests, i have higher vacuum over all and 22 - 23" in OFF position on CCU. All modes appear to function normally but my A/C system was disabled (no belt on compressor) so i can't test that portion.

Now the engine shuts off as it should! I am still in troubleshooting mode as everything is dismantled and want to finish the job! I don't know if i am dealing strictly with a vacuum leak, switchover valve problem or missing check valve(s).

Purple (vi) line cut before the T, after leaving port #2 of device #2 (lower left-hand section of drawing)

Worked with easiest access circuits first:
Capped lines orange and green at #44 - still reading 7" on vac gauge
Capped green line at #43 - still reading 7" on vac gauge
Capped black line (port #3, from device #2) at 3-way junction - still reading 7" on vac gauge
Capped purple line at splice point - vacuum gauge reading 22+" for all tests.

Just an update - shutdown problem located at leaking DEF pod or related vacuum lines/connections. DEF (white) located on left side, pink pod is for center vents. Have order4ed a "pod popper" which allows diaphragm replacement without removal. We will see how well it works as there is very little space under the center dash. DEF pod has 2 diaphragms - what fun!

No 40 is center vent pod, 42 is DEF.

Any 116 owners out there following the procedure for servo maintenance (flushing with clean water) per the original post from Dokter Bert?

I am still running a Mantis servo (aluminum) I bought in 2004. It has always worked perfectly. Recently, I have noticed a 'weep' from the lower portion of the housing where the water manifold bolts up. Other than that, I haven't had any problems and that's driving the thing everyday.

To reiterate...

Most times, I find a 107 or 116 in the junkyard with the aluminum servo and they work perfectly, because the ACC II system failed as the result of another component failure in the system.

#1 customer complaint on the ACC II was #3 and #9 fuse failure, which in 90% of the cases was a shorted A/C low pressure switch.

#2 most common customer complaint was the system switching from hot to cold, which was a rotted in-car temp sensor hose.

#3 most common customer complaint was the A/C switching to full heat when the temp wheel was moved. Most common cause was a 'dead spot' in the wheel's resistance curve.

In all the years I worked on these, I can think of only 5 servos that I replaced to get them working correctly.

Hope this post helps....Robert

Hey Doktor Bert - Did you ever resolve your kick down issue on your 116?