I just bought a '83 300SD and I'm having a little trouble with the climate control. When I put the heat on it blows warm in the front but the vent at the back of the console continually blows cold.

Am I doing something wrong?

There is a lever on the rear vent that I slid all the way to the right. This turns off the cold air coming out here. In the summer, I might open it, if it's blowing cold air-conditioned air. If I was really worried about it, I might get the servos checked, but the system works.

Also, I get a fairly wide variation in temperature of the air that comes from the dash vents. Once on a long trip last winter it annoyed me enough that I turned the fan to "low" once the interior got nice and warm.

I think that the climate controls are a weak spot in these cars, but if it can be adjusted to give you heat and cool air as appropriate in the correct amounts, it's working.

The whole climate control system, to me anyway, is a bit mysterious. At least the system doesn't have to be constantly adjusted; the automatic temperature setting is cool.

__________________
Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic

AS Robert stated the rear vent allows only cold/fresh out. Many times the lever doesn't shut the air completely off. IT can be adjusted.
One of the most important items for the A/C/C system to operate correctly is the in-car temp sensor, air has be be drawn across this sensor. MB used a foam rubber hose & they fall apart after 5-6 years. Without air flow across this sensor the system operates slowly. Cars after 84-85(depends on model) used a electric motor to aspirate the sensor. At dealer we retro-fitted this motor to the 1985 W126 chassis. I have installed this set-up on many cars so that system can operate & give EVEN heating/cooling. When the sensor was moved to the roof area the systems worked much better.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

This is from way back, but is this true? My rear vent only blows cool air and I'm sure they designed it to blow whatever air is blowing out the rest of the vents. My side window defogging vents (but not the ones below it) don't seem to move much air. I'm wondering if they are related. Evertything else seems to work just fine.

I'm sure "closing the vent" is a solution to blowing cold air, but not a solution to get it to blow warm if (that is, if it is designed to.)

Thanks,

__________________
B
-
1983 300SD

I'm quite confident that you can believe whatever M.B.Doc tells you.

I'm with Brian on this. If M.B. Doc says it you can take it to the bank.

__________________
Jim

My understanding of the W126 and the diagrams. Someone correct me if I am wrong. Cool/Fresh air is all that is available from the center rear vent. Rear heat is ducted to the feet only (there is a duct system that runs under the front seats).

If the control lever at the rear center vent doesn't shut the cool air off, then more than likely a clamp has popped loose from one end and the cable jacket is not anchored. The other end of that cable can be seen by pulling the glove box and looking at the right side of the center plenum with a flashlight. (I just had mine apart a couple of weeks ago for a pod repair.) Who knows you may be able to fix it with minor disassembly!

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

yep, non-heated air only to the rear center vent. The owner's manual states this too. If you pop the ashtray + money tray assy out you can see (and reach) where the front end of the cable wire attaches. The sheath is held by a spring clip. SD Blue, I have my center console out right now. Any sage advice about checking/replacing that center pod would be greatly appreciated. I figure I should do it now.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

If I recall DMorrison has some photos of this but I don't recall how long ago.

To remove it you will need to pull the ACC controller and center vents. Also, removing the glove box liner is good spot for some light. It is a good idea to plug the lower area with some rags or something because parts can disappear into the great black hole.

Remove a couple of the plugs and the rubber flex ducting away from the right side of the center vents. To remove the pod itself, there is a small portion of the plenum that is attached with very small screws behind it. Once they are removed,(long 1/4 dr. wobble ext.) you can pull the pod and mounting out enough to see the actuator rod. Push the rod to the left and it should pop out of the clip. (this clip is the same type as the one on the top right side of the plenum for the defrost actuator rod)

Once you've rebuilt the pod, I found that some light wire, looped through a small hole on the flap, and some hemostats held the flap down in order to reinsert the actuator rod.

It is a bear because you have to see what you are doing, insert several tools and work in an area about the size of a wall outlet.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

Sam, did you actually rebuild your pods rather than replace them? I'd really like to do that as it would be a nice $ savings and I always like to take things apart so I can see how they work. But I've read several threads on this forum that indicate that "rebuilt" pods didn't work out properly and only new pods would fix it right. If you rebuilt your pods, who did you get the diaphrams from? And are you happy with how they are operating? Thanks!

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Yes, I rebuilt the pods with diaphragms from www.autoluxmbz.com I believe it was about $50 for all new rubber and the little tool. Having not worked on any other Benz, I am not sure if there were different pods, but the new diaphragms worked fine for me. There are two different types in the kit, and that may be the problem others have encountered in the past if they did not get both.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

1984 300d Turbo 138k
Some Of The Vacuum Pods You Can Replace, The TWO Units ONE Best To
Buy New Actuators, The Center Ones Remove The Two A/c Vents And Remove Glove Box And Pop The Linkage With Long Flatrewdriver USE SMALL HANDS AND CAN FEEL YOUR WAY TO REMOVE AND INSTALL And Turn Unit Ccw Or Remove Small 2 Clips Do The Ones Behind The Glove Box First Singe Units, The Foot Well Actuator Is A Pain, Remove Pass Side Panel, Long Flat Screwdriver Pop Linkage Lever Use Water Pumps Ccw Drivers Side And Remove When Install Use Your Fingers To Press Linkage, SNAPS IN, Line Up Actuator First And TURN CwTo Snap Drivers Side In Place Plug In Vac Line Done

I don't mean to hijack this thread, but I have a quick climate control question. I read above that later models had an electric fan for the temperature sensor. Can you fit one of the sensors with the fan into an earlier dash? My sd CC is realy slow to adjust temperature.

__________________
"spreading a trail of obnoxious where ever we go"
1981 300sd w/ 341,500 miles

http://www.wecrash.com/pics/ddda_banner.gif

I'm now getting the urge to pull my console apart, for multiple purposes of upgrading the stereo and maybe replacing that foam ACC hose that goes to the temperature sensor.
Any other caveats/advice for pulling things apart?
I've never been into my console for anything, my experience being limited to pulling out the ashtray and R&R'ing the one window switch in my old blue 1977 300D...

__________________
Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic

Can anyone describe what each pod controls? Which one is for center vents side vents, recirculation ect?

__________________
1982 240D 370,000 daily driver, great car!
1983 300SD
1995 350SD gone to rod bending heaven.
1986 300SDL should have never sold it.
1995 2Dr 4x4 Tahoe with a highly modified 6.5 turbo diesel, 6in lift.