I'm under the hood of my 86 300E trying to trouble shoot the climate control system. I've printed the sections from the CD that are appropriate for the job (83-620) and I'm very disappointed with the quality of the pdf files. The pictures showing the component layouts in the engine compartment are all but unreadable.

In particular, I'm trying to find the Y7 valve block and the vacuum reservoir (which is supposed to be under the left front fender.)

I'm guessing that I need to pull the air filter to get at some of these things? Guidance?

Thanks!

Sean

The reservoir is inside the fender (I think as in thousands of repairs I have never needed to see it).

The switchover valves are behind the glovebox.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Are you having problems with your climate control?

If so chances are that the problem is inside the car... related to the controls, rather than under the hood. Why are you looking for such an exotic part?

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Earl



1993 190E 2.3
2000 Toyota 4x4 Tundra

Yup, all sorts of problems.

I only get heat out the defrost vents, never to the floor or out the main vents. I only get heat some of the time, and only when the temp wheel is at what I presume to be Max (the wheel itself has no numbers so I can't tell what the temp should be.) It gets hotter than blazes when it's on, and adjusting the wheel for some other temp makes things awfully cold. The fan switches do seem to cause the fan to run in a way that seems right (i.e., on all the time, varying speed, and free wheeling).

In operation, I also hear some "clicking" that seems to be coming from the driver's right side, perhaps behind the glove box or footwell on the passengers side? It seems like that may be the "controller" trying to switch flapper valves around to regulate the temperature, but since there's no vacuum, the temp can't be regulated.

From the symptoms and the reading that I've done on the on the CD, I've concluded that I probably have a vacuum problem of some sort. I bought a MityVac and started troubleshooting today.

I've been pretty faithful about following the steps shown on the CD (83-620), So far I've found that

Step A
1) the check valve seems to be ok
2) the vacuum reservoir holds no vacuum at all

Step B
seems ok per the MityVac

Step C forward looses vacuum at all steps. I'm not quite sure what this means yet, but my guess is that there is probably a problem with the main vacuum supply line, maybe going to Y7? Since I couldn't easily find Y7 and it was getting too dark and cold late this afternoon, I decided to call it a day.

I'm also really disappointed with the expensive CD that I bought from MB. The detail on the pictures is horrible, both on screen and printed. I'd have thought that the quality would be better.

Thanks!

Sean

The bad news is...the dash has to come out! That is a lot of work!
Do a search an good luck!

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J.H.
'86 300E

I have an 87 300E which had similar problems. All were solved withe repairs made to the controls. The controls are the buttons you push and knob that you turn.

The job is not too difficult and you start by removing the ash tray. Remove the screw behind the ashtray that holds the wood grain panel cover and then continue to remove screws untill the you have access to the controls.

The problem will probably be with the wheel that sets the temperature.

Do a search on all of my posts because I give a detailed proceedure on how to fix it. I did the job some years ago and now forget the details.

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Earl



1993 190E 2.3
2000 Toyota 4x4 Tundra

Also.. you might some electical cleaner spray (no rsidue and safe for plastics) at radio shack or elecric supply store. Us to clean any contacts behind buttons.

Also make sure parts of the controls are aligned properly... needed for secure electrical contact.

You can buy a new wheel assembly from parts shop or repair the old one per my previously posted instructions. I forget how I made the repair but it was common sense with a little ingenuity.

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Earl



1993 190E 2.3
2000 Toyota 4x4 Tundra

What an awesome forum and helpful folks.

J. Hidalgo got me looking into removing the dash (yikes!) which led me to this post:

W124 climate control vacuum pod replacement

which describes a problem with high mileage 124's and corrupted vaccum actuators (i.e., with holes in the rubber diaphrams) that cause the ACC system not to work. He's made available lots of pictures at

http://www.meimann.com/images/mercedes/W124_dash/

I'm off to look into Earl's suggestion that the problem is the temperature contol switch. I've actually been inside this part of the dash recently as I've replaced a non-working aftermarket radio.

Guess which one I'd rather be the problem?

I need to ask again: the MityVac shows that the vacuum reservoir (now out of the car and on my bench) will not hold a vacuum. Though I'm sure it's a part that fails rarely, doesn't this suggest that it's a likely candidate for replacement?

Thanks.

Sean

Hi again.

I just found the post that you were talking about Earl, and it may address part of my problems, but I don't think it's the whole solution - bummer. I will take the control unit out tomorrow tomorrow morning and look at the wheel, though since it doesn't have any numbers, I don't think a repair will do the trick - assuming that it is the problem and I could do the resoldering as you did, I'd still need to get a new switch so that I could see what the scale is.

Looks like I'll be ordering a new switch and new vacuum pods, and spending next weekend in dashboard hell!

Thanks again all.

Sean

I am not familiar with how the vacume reservoir works. I would think that it is only supposed to create a partial vacume and only when the control buttons tell it to do something. If so it would only need a partial vacume for a few seconds... for opening and closing vents. Holding a 100% sealed vacume may not be necessary.

But I'm just guessing. The design should give you a common sense clue as to the nature of the vacume required.

__________________
Earl



1993 190E 2.3
2000 Toyota 4x4 Tundra

I remember reading somewhere that you can buy just the stick-on ribbon that is missing from your wheel. Maybe at parts shop or a dealer.

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Earl



1993 190E 2.3
2000 Toyota 4x4 Tundra