I have a '82 240D with factory a/c. Yesterday, I was trying to diagnose a vacuum leak that has occured ever since I purchased the car a couple of months ago. I believe I have found it. From the engine compartment, I traced a brown vacuum line that would not hold vacuum. I took the bottom kick panel that surrounds the brake pedal so I could see where the line lead to in the passenger compartment and found out it leads to no where; the line was just sitting just beside the brake pedal with a rubber nipple at the end like as though it was connected at one time to a fitting.

I found out through this forum that the brown vacuum line is for the climate control system. My car has the three manual rotary controls. Two conrol temperature (manual cables to adjust coolant to the heater) and one control for fan speed. Also, along the rocker panel switches (for antenna, sunroof, etc) there is the vertically mounted a/c control wheel (to adjust the a/c temperature).

I tried to locate where that brown line connects to but could not find where it would go. At first I thought the vacuum line may mount on to the vertically mounted a/c control wheel but there is no vacuum line connection there to receive a vacuum line. I did check the recirculating vacuum flap actuator just above the fan area; it had a green vacuum line with yellow striping connected to it and it is working properly.

I was wondering if the MB techs or anybody in the forum could help me with this problem of locating where exactly does the brown vacuum line lead to. Many Thanks

Herb Rocha
82 240D
106,000

Where is the other end attached? The brown lines are usually for the "shut-off" function (not climate control or A/C, these are green). I presume your car shuts-off or you would have said so. This makes me wonder if some lines have been switched. There should be a black line coming inside and going nowhere. It is the vent for the proportioning valve (goes inside to pull clean air) mounted on the back of the injection pump. Of the two lines attached to the proportioning valve the one that goes inside the dash is the one that comes out the side horizontally.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Steve,

You are right. The hoses were switched by the previous owner. Instead of the brown line leading from the engine shut off switch, a black line was added from the ignition switch to the vacuum line. THat was what threw me. Thanks so much for the advice.

Herb Rocha
82 240D
106,000