PeachParts Mercedes-Benz Forum - 300D will not shut off unless I blocked this line

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300D will not shut off unless I blocked this line

There is a thread here on car won't shut off and the problem may be similar to mine. My 300D will not shut off unless I unplug the green line and block the vacuum source. The green line goes to the ignition switch somewhere.

I have this problem for a while but I just procrastinate. I will try to fix it over the holiday period. Where does the green line connected to? What is faulty?

The picture shows the vacuum line. Your help is appreciated.

Well, it's one of three things: door locks, ignition switch, climate control. The door locks appear to be plugged in according to your picture (it pass thru that splitter valve thingy first), and the ignition switch has to be plugged in otherwise it wouldn't be shutting off.

That leaves the climate control. Nice little pink vacuum pods scattered all over under the dash, for controlling air vents. Maybe if you remove the kickpanels you can reach some of them for testing. You can also get to some by removing the glovebox.

The green line goes to your climate control. Probably one of the pods is leaking.

Quote:

Originally Posted by ImBroke (Post 2366395)

The green line goes to your climate control. Probably one of the pods is leaking.

Agreed.

Quote:

Originally Posted by aaa (Post 2366393)

It is not the door because all the doors can be locked/unlocked OK with the line plugged. Climate control, may be but A/C and heat seems to be OK. When I 'T'ed a Mityvac to the green line ( car not running and line has vacuum ) and I switched the ignition switch to 1 or 2 ( cannot remember ) then the vacuum is gone. That was why I unplugged the green line and managed to fix it.

Does it indicate the ignition switch? How easy it is to fix? What does it entail?

Thanks.

It's the climate control. All about the vents, and opening/closing them according to the buttons. So do the defrost vents block off air when it's not turned on? Do the center vents open when they're supposed to? Etc.

aaa. Thanks.

I will try to remove the dash underside panel and take a look. I am not sure about the defrost or center vent as I do not take much notice to them.

There's a guide on the wiki:

http://www.peachparts.com/Wikka/W123HVACVacuumActuators

I'm not sure how accessible the vacuum tubes are but if you can get to the right ones easily you'd be able to narrow down which side of the car has the bad pod, as opposed to testing every pod.

Yep... Green is the ACC line. Pulling the drivers knee panel and the glove box will allow you to test most of "actuators". You can actually buy new diaphragms instead of replacing the entire actuator $$. There are also quite a few vacuum elbows in and under there that can be torn, cut or rotted. Some are a PITA to get to and are behind and below the center vents. More than likely that those are OK.

If you don't have a mighty vac yet.... Now would be the time to get one. The system is pretty easy to troubleshoot once you learn all the lines and where they go. I have become VERY familiar with it lately:rolleyes:. But, I can say that "everything works".

Get round to take a look at this problem and there is a tip or 2 I can share with the forum. The green line goes to the 5 control solenoids behind the Climate Control. It is a challenge to find out which one of the 5 pods is leaking. I find a quick way to do it.

1) Remove the 5 holding screws on the CCU faceplate. Move CCU aside but do not undo the 2 big plugs on either side.
2) T the Mityvac to the green line
3) Unplug ALL 5 connectors to the vacuum control solenoids.
4) Start the car and monitor the vacuum level, the level should be normal as all the vacuum solenoids are off ( not connected ).
5) Plug the connector back in one at a time. The vacuum would drop once the connector associated with the leaky pod is re-connected. You may need to vary the CCU setting to make sure the control solenoids are activated.
6) Optional - It is also possible to hook up 12v to the solenoid with a spare connector as the CCU setting may or may not energize the solenoid.
7) This method saves me a lot of time as the vacuum tube is a PITA to get to behind the CCU and I do not want to remove the glove box panel to test the pods.

I managed to locate solenoid number 1, the left-hand most one. The vacuum dropped once I re-connected the solenoid. It was so easy to identify the culprit. The pod is underneath the driver panel.

Any one can tell me what does #1 pod control?

Quote:

Originally Posted by ah-kay (Post 2891794)

If by "underneath the driver panel" you mean just to the right of the driver's right foot, it's probably the defrost pod.

Or, it might even just be half of the defrost pod since there are two diaphragms in there. Or, just to confuse you, it might be the feed line from the center pod to the defrost pod since two lines actually go to that pod, but it is possible your diagnostics isolate the center+defrost line.

If it's the smaller pod in that area with one line, then it's the footwell flap actuator pod.

http://www.peachparts.com/shopforum/general-information/295241-scans-airflow-w123-climate-control.html

Quote:

Originally Posted by Yak (Post 2892243)

Thanks Yak.

It is the pink color Pod on the right of the gas pedal, the right foot. I have some time this week so I decide to take a look at the 2 years problem as the vacuum pods is a PITA to get to. I am quite pleased with myself as I do not need to remove the driver's or passenger's panel to locate the leaky pod. I removed the driver's side panel, plugged the vacuum hose going to the pod, reconnected the green hose and now the car shuts off OK. I will take a look at the pod, or half the pod, sometime, don't know when though. Will report back.