I just returned from Florida and several issues popped up including this one: Somewhere during my stay in FLA the ACC system went wonky. The main clue is while the AC worked fine, the return to cold weather resulted in no heat to the floor vents. This is accompanied with harsh upshifting from the transmission and an extremely harsh downshift when decelerating at about 5mph. Truely a joy in the heavy traffic I experienced and I am sure beneficial to the loose axles I reported in another post. Anyway I know I have a vacuum leak somewhere in the ACC system, and from the searches I have done it is likely one of the ACC servos. Plenty of heat out the side vents, the centers were off as they should be with heat on, and no heat out the floor vents. The search posts indicate that one of the ACC servos is leaking but does anyone know exactly which one would do this? Also so the search posts mention a gentleman named "George" and his repair kits for the ACC servos several times but with no contact info. How do I contact George? Thanks, RT

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When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K

I don't think your car has the type of climate control servo that George Murphy repairs and also manufactures.....That servo is under the hood and has about 12 electric wires and about 10 vacuum lines going into it...it stradles a set of hoses where it controls hot coolant to your heater...That servo is not in the 82-85-300D Turbo......I have seen it in a 1978-300D...Do you have that type of servo???If you need Geoge's phone number or address I will find them for you...His operation is in Oak Ridge, TN......Jim

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James A. Harris

I think the thing you might be thinking of is what some refer to as a "vacuum pod". Others call it a "vacuum element". I replaced the one for the floor vents on my '85 300D. I used FastLane part # O4010-73599, which is described as being for the "legroom flap", and it seemed to fit fine.

This vacuum element is oriented horizontally, and is located down low and behind the stuff in the center console. I think that removal of the underdash panel on the driver side is enough to get access to the vacuum connection so that one can test the vacuum element with a Mityvac. Removal of the underdash panel on the passenger side gave enough access to the moving part of the vacuum element from the linkage that actuates the flaps (not necessary for testing, just for R&R of the element).

RT, don't jump to a conclusion that the leak is in the CC system just yet. IIRC, there is a restrictor that prevents a leak in this system from screwing up everything else on the vehicle. If the entire vehicle is affected, and it appears that this is the situation, do some basic checks under the hood to attempt to locate the leak. It might be a very simple leak on a vacuum hose from the pump. In any case, if you believe that the CC system is at fault, disconnect and isolate this system under the hood and be sure that the trans. returns to proper function before you struggle with something in the CC system that is not broken.

Check what Brian said, then if your leak does end up being in the ACC system, feel free to PM me and I'll talk you through finding it.

I have had a bad switchover valve and center servo leak before, currently the servo at the far right of the dash is leaking- i just plugged it for temp. use. had to pull the dash before to replace the center one!

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

No heat to the floor vents is usually a lower vacuum pod problem but I agree with the others that you should double check the main system first. The pods should be rebuildable on your car but it's a bit fussy if you still have the original pod since the plastic can be a bit brittle. The rebuild kits are available from George on his website here: Autolux Inc. and worked for the floor vent pod on my '85 so it should work on your car. You'll definitely want to remove the kick panels on both driver and passenger sides in order to get the pod out in one piece (unless you are double jointed at the wrists).

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold

Okay, finally got to doing some diagnosing with the Mityvac. I have two problems. First the vacuum tubing that runs across the front of the engine to the EGR controls on the passenger side fender had contacted the water pump pulley and that caused a major vacuum leak. I fixed that and disconnected the green vacuum line at the firewall and plugged up the line. Test drove the car and it shifted wonderfully, silky smooth just like always. I connected the Mityvac to the green vacuum line and got these results:
ACC unit off = vacuum good, no leak
ACC unit on any other setting, cold or hot = didn't hold vacuum, leaked down fast. It leaked down extremely fast in the defrost setting.
I was able to keep pumping the Mityvac to keep up with the leak in other settings and when I did this I got heat to the floor vents. Once the vacuum bled off the floor vents closed. So whats this all mean? I am going to take what I can apart and start testing the individual vacuum elements with the Mityvac to see if I can figure out what is leaking. Any input appreciated. RT

__________________
When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K

I have had these problems, and I have your same year and car.
The best way I have found for having to test the pods is to simply remove the climate controls and then the switches above them, exposing the switchover valves. From there you can test all the pods and lines to find which is leaking. It could be just one or quite a few.
Off the top of my head, I don't know which changeover valves are for which pods, but I am pretty sure it has been said here before. Just test the lines with a mityvac or whatever and find out which ones are leaking. The changeover valves are numbered from the left, and for me, there were even stickers on them with the numbers. Don't know if the PO added them or if they were there originally.

Also for your reference:
changeover/switchover valve 1: defrost full
2: footwell flaps
3: center vents and defrost half
4: recirculated air flap
5: main air flap