Climate Control Leak
 

I have a quick question about a vacuum leak within the "green" line (climate control).

When my dial is on heat (red), the car won't shut off. When it is on cold (blue), the car shuts off fine.

I went into the engine compartment and plugged the splitter where the green line comes in and thereby isolated the leak. My question is:

"Is there some type of vacuum acutuator in the behind the console similar to the door locks?"

Thanks,

Don

I very recently replaced an ACC switchover valve in my '85 300D. These are in the console behind the pushbutton climate control unit. After I had taken the valve out (leaving the vacuum line open), I decided to test the voltage going to that valve's electrical connector to make sure that the climate control unit was sending the right signal to the valve. The suspect valve was the one that controlled whether the leg flaps would open and let heated air out. After I found that manipulating the temperature dial would send voltage to that valve, I tried to turn the engine off but it wouldn't because of the open vacuum connection which I had not yet hooked back up. The engine stopped after I plugged the vacuum line with my finger.

My experience leads me to think that the problem you may be having occurs because a vacuum line or diaphgram downstream of the appropriate heating-related switchover valve may have a leak in it. When the climate control unit opens up the heating related valve to allow vacuum to activate a flap, the leak doesn't let the engine shut off. If the temperature dial is in the blue, then the heating-related switchover valve doesn't open and there is no leak.

That's my guess, but I am pretty new to this...so consider the source.

Good luck,
Dan

Same here
 

I had the same problem yesterdayon my 85 300D turbo. when I was trying to change my defrost change over valve. I think if the vacuum line comes off the change over valves, you will not be able to shut off the engine under certain conditions based on which valve connection has come off.
Did you do any work on the car recently. Once I had a complete shut off problem( car wont shut off at all) after an oil change and I found I had accidently disconnected a vacuum line from the 4 way rubber connector. Push all the lines nicely into these connectors before you go for checking the change over valve connections.
does your door locks open and close normally? try about 10 times while the car is running. If they dont hold the vacuum then you most likely have a problem in one of the connections in engine compartment.
Good luck
MVK

Thanks:

I've isolated the problem to inside the cabin because if I cap the green line in the engine compartment all is well. All other vacuum lines are hooked up and functioning. I don't think there is a leak in the hard (green) line itself as it works fine on blue. Perhaps the mechanism that it leads to is bad.

Don