Climate Control Fix - PeachParts Mercedes-Benz Forum

pj67coll · #1 04-03-2014, 03:12 PM

I've never owned a Benz yet with the awful US style climate control setup. All mine including my 80 116 had the Euro manual sliding levers and knobs to open and close the relevant air flaps and stuff. However I'm well aware of the frustrations the US version involves and as I hope soon to acquire one or two examples I've been considering this topic quite a bit.

There are numerous threads and online resources concerning removal and repair of the heater/air box's and their vacuum pods but I'm always left with the feeling that even if working properly you still have these inaccessible vacuum pods sitting buried in the dash ready to sabotage your system.

Wouldn't it be possible to disconnect all the vacuum related stuff from the pods themselves and just run Bowden cables to each air flap or to the pods that control the flaps? So that air flow can be directed as required merely by pushing or pulling on a knob that has a cable attached directly to that flap. Also you should be able to remove the evil servo completely then and run a line directly to a valve installed in its place to allow heat or no heat as required.

For myself I'd assume all these cables could be routed to the location of the ash tray on the center console. To me it's just wasted space as I don't smoke. So what you are doing in this case is reverting to an all manual system, both for heat and ambient air and air flow direction. For A/C of course the system would work fine with the heater valve closed off.

Any thought's on this concept?

- Peter.

aieeegrunt · #2 04-03-2014, 03:28 PM

This sound awesome and if somebody comes up with a good method to do it I would be all over it

mach4 · #3 04-03-2014, 03:37 PM

Someone was talking about using servos to control the flaps. If so, the automatic functionality of the controller should be able to be maintained, i.e instead of actuating a vacuum solenoid, it would activate a servo.

SD Blue · #4 04-03-2014, 04:49 PM

Sheesh, all that work to convert to manual controls. To convert, you will likely need to remove the dash anyway so personally I don't understand why go to a considerably bigger headache. I know the manual system sounds simpler but a conversion certainly is more than most people realize.

I refurbish the ACC system on my W126 with new pods and really enjoy how well it works. (I know the W126 is easier than the W123.) I did the entire system in a couple of afternoons.

Just some thoughts to take in consideration.

cooljjay · #5 04-03-2014, 04:51 PM

I don't think this would be possible, as the heater box doesn't have the necessary attachments for cables...and to install these cables one would have to disassemble the dash entirely to install the cables. If I were to go to this much hassle, I would just install a manual setup.

I am also thinking in my head, that as long as you are using the system the pods won't sit idle enough to rot....on my 78, I have all the original vac pods and all the original door actuators.....none of them have ever failed in 35+ years...

I feel confident that once the evil acc is tamed, it will last many many moons....I have had no issues with mine since I fined it over 2 years ago...granted I still need the ac fixed and my blower motor had issues...

pj67coll · #6 04-03-2014, 05:36 PM

Quote:

Originally Posted by cooljjay

I don't think this would be possible, as the heater box doesn't have the necessary attachments for cables...and to install these cables one would have to disassemble the dash entirely to install the cables. If I were to go to this much hassle, I would just install a manual setup.

So how do the pods attach to the air flaps then? You might be right and it may be too much trouble. But in order to swap in a manual setup you have to have a manual air box to replace the original with. My theory is that this way you just have to change the mode of operation of the flaps on the existing air box.

I know you have to remove the dash etc to get at all this stuff. But I'm thinking that you might be able to get away without having to remove the actual air box itself which should make the job a little easier, perhaps, maybe, or something...

- Peter.

Junkman · #7 04-03-2014, 08:52 PM

You're going around the world to cross the street. Refurbish the system and move on. It isn't that difficult once you decide that you want it fixed. The car becomes trouble free once you take care of the neglect. Do the entire system the 1st time and be done.

Sometimes you'll find an alternate part that works. I saw some 1\8" air brake line in 100' rolls that may replace the brittle vac lines. It will also plumb a pressure gauge useful for adjusting the trans and installing a boost gauge. It may be enough to do both SDs, the Cummins fuel pressure gauge, boost gauge and the Datsun Z boost gauge. Other sizes are available also!!!!

macdoe · #8 04-17-2014, 02:09 AM

Does anyone here know if second gen w126, underdash vacuum pods are the same units as used in earlier w123 cars? I am interested in having the climate control work properly in the 85 300TD and have access to a 1988 420 sel heater box that has already been removed. The pods look in good shape from these donor parts, if they would fit? I am certain there is a footwell flap broken and the heater core may be leaking in the wagon....anyway to look at it..the dash has to come apart. I do have a manual climate control box and everything else to covert it to manual, but if it is just a matter of changing a couple pods then maybe that would be easier...but, does the entire c/c box have to come out anyway, if it turns out the heater core is in fact leakiing?

yvairguy · #9 04-17-2014, 03:32 AM

I have wondered about retrofitting a climate control system from a tacoma truck it looks like it would fit then you can have all electrically controlled valves, they even have a cabin air filter.

Mxfrank · #10 04-17-2014, 06:50 AM

I see no problem here, just a lot of hand flapping. The stock pods are good for twenty or thirty years (mine lasted 26). It's a big job to remove the dash and replace all the pods, but not one that has to be done often. Sure, you could replace all five vacuum pods with cables. But you'd have to pull the dash to do that anyway. And you'd be left with a control panel that looked like it had been hacked together by a teenager in metal shop. Since this isn't a problem you have, you can avoid it by not buying the car.

zorecati · #11 04-17-2014, 07:36 AM

I'm with the majority on this one. My car is an 87 and other than a hose popping off one of the pods, which I caused, the system works well. I'm not seeing the benefit of hacking up a decently engineered system.

jay_bob · #12 04-17-2014, 10:00 AM

The ACCII (Chrysler-based, aka the "evil servo) system was a crime against nature. MB engineering was undoubtedly pushed by marketing to come up with an automatic climate control to match the US domestic offerings. In a collaboration that was only a harbinger of awful things to come 20 years later, they reached out to Chrysler and they (probably as a joke) sent them the design for the ACCII. It was used up through 1980.

Starting with the 1981 MY up through the early 90s they used the ACCIII (with the horizontal buttons).

If you have the ACCII there are solutions out there to get it going again but they are very expensive.

If you have ACCIII that is one of the finest examples of analog control engineering out there. It is not difficult or expensive to get it right again. The troubleshooting procedures are located online for either the 123/early 126 or the successor 124/late 126 version.

Most of the time the problem is a bad temperature sensor or a leaky actuator pod.

I'm an originalist, my goal is to try to keep the car as original as possible yet be practical about it. It's a testament to the engineering that went into these vehicles.

pj67coll · #13 04-17-2014, 11:06 AM

Quote:

Originally Posted by jay_bob

I'm an originalist, my goal is to try to keep the car as original as possible yet be practical about it. It's a testament to the engineering that went into these vehicles.

I agree. But as regards the US market climate control I don't think it's a question of "engineering" More as you mentioned a kind of a sick joke on Chryslers part. Living in Phoenix it's remarkable to see so many older Mercedes driving around with their windows down for most of the year. A testament to the "engineering" that didn't go into the climate control...

- Peter.

jay_bob · #14 04-17-2014, 05:41 PM

True. If you have the evil servo you really don't have much choice.

My comment about trying to keep it original is more directed at the ACCIII system which was superior to the ACCII system. The ACCIII system is capable of being easily fixed to the point of being reliable.

If you have the ACCII about all you can do is install an aftermarket servo control box. I saw the link in a thread on here a while back. It costs something like $700 but it makes the system work properly.

For the uninitiated, the ACCII can be identified by one of two ways:
- a control panel that looks like it was homemade with Radio Shack parts, the air flow buttons are in a vertical column, and a giant ugly rocker switch to turn the compressor on and off.
- a device under the hood that looks like a sci-fi robot's head, with wires, vacuum hoses, and coolant lines all connected to it. Yes, coolant, vacuum and electricity converge in the same device. What could possibly go wrong here?

Mxfrank · #15 04-17-2014, 06:41 PM

I had that system in my old 300CD, and it wasn't any harder to work with than the later system. I'm surprised that Chrysler was involved in this, as it isn't similar to contemporary Airtemp designs with which I'm familiar.