I have been working on a non working center vents issue. I will wait to have time to remove dash but in the meantime I did a "interim fix" I found in my research. First off, I could not possibly get me hands in through the glove box to grab hold of any pin or actuator to prop up the flap like I read others have done, so I just propped the vent open by sticking some heater hose on its side in there for now. I am getting air through the center vents. Not great, but better than nothing.
My question is I did not disconnect anything else. I read about vacuum?? Do I need to do this? If so what do I disconnect and do I plug it with something? Thanks

Subscribed .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

What is "subscribed". Thanks

It means I have signed up to this thread so when others write to tell you what to do, I'll get notified and read and learn along with you .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

The center vents only come on when the climate control calls for cooling. They default to close. When the CCU tries to cool the cabin, they should open by applying vaccuum to the actuator that you can't get your hands on.
When I had that issue, I used a long set of forecepts to remove the vac line from the actuator. I plugged the line into a vac guage that rested in the glovebox compartment. That allowed me to verify that the CCU was functioning, (it was) then I removed the vac pod and replaced the diaphram. I did manage to remove the actuator without removing the dash, but it has been so long ago I forgot how I did it. I remember it being a PITA that involved pushing the rubber boot that connects the vents to the ductwork out of the way so that I could get another hand in there.
I am pulling the dash on my current project and replacing all the actuators at once, cleaning the evaporator, replacing the radio, replacing the cruise amp, and and other various parts that are hard to get to all at once.

__________________
1985 300 TD 448K
1984 300 TD 278K

1983 240D euro 240k
1994 f-250 idi turbo 330K
1986 f-350 IDI
1987 F-350 IDI

1985 JD 1050 4wd
1965 IH 3660

The problem on my Klima II equipped 300TD is : the dahs vents only blow air when set to cool air in the 'EC' (non air conditioning) mode ~ as soon as I press the AC button on the PBU the vents stop blowing any air....

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

I am still a bit confused? Does it do any harm to have the center vent propped open without disconnecting anything else?

Your silver box behind the glove box is likely bad. If the vents open at all under any circumstance, you likely don't have vacuum issues. The other possibility is bad vacuum pods on the recirculate flap (feel for air leakage through the defrost vent).

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

As stated above, the center vents are supposed to close in certain modes. What mode are you in and why are you trying to open the center vents? If you're in heating mode (white area on the temp wheel) the vents are SUPPOSED to be closed, heat only blows from side vents floor and defrost.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

The center vents always stay closed no matter what buttons I push (or modes I am in) I just wanted them to open in the AC position. The AC works but only comes out of the sides and defrost. Now that the center vent is "propped" open I get some air flow (although not great, but at least some)through the center as well. I am just wondering if this is doing any sort of harm having the flap propped open? Thanks

No, it isn't harming anything having it propped open. You shouldn't be getting A/C through defrost. Check your vacuum supply at the input to all of the various vacuum switchover valves. It sounds like you have a weak or non-existent vacuum supply.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

As was stated, sounds like you either have bad vac pods all over (which is not unlikely if they have never been changed) or you have low vac. Propping the center vent open doesn't hurt anything, but you won't get much airflow out of it till you close off the defrost. That pod is to the right of the go pedal in the center console. It is much easier to get to than the center vent and might help your airflow till you can get to your center pod.

__________________
1985 300 TD 448K
1984 300 TD 278K

1983 240D euro 240k
1994 f-250 idi turbo 330K
1986 f-350 IDI
1987 F-350 IDI

1985 JD 1050 4wd
1965 IH 3660

Whoa hold on there not so fast. I’ve changed center vent vac pods in both my 123 and 126. They were bad. Wait, oops sorry Diseasal, that’s what you just said.

Agreed the silver box can also be bad too...but test, don’t guess. On the 123 take off the HVAC button panel and get access to the switchover valves and manually vacuum each flap actuator with a mityvac and observe what it does. The center vent can be seen easily with a flashlight looking in the front. The bad switchover valve coils were open and there were burns on them. Tested easily with a 12v battery or ohm meter.

I had 1) a bad silver box, 2) a leaky pod, and 3) a burned out switchover valve. Yup, all three on my 300d.

Luckily I have small hands and can reach up on the side of the glove box to get at the center vent. I had to also work from the speedometer side as well. (Take out the speedo and work from the left hand side of the vent.

But first before cutting up your wrists in there, mity vac the circuit and make 100% sure you have a leaking pod.

I have some photos of the diy tools and process in my 300d thread. Oh yeah and you also need to peel back the rubber duct work back as mentioned by shadetree. Another trick is to get the linkage holes to line up for the pin I used a mityvac to manipulate the pod. You need to pull it way back before it’ll snake up there into position.

http://www.peachparts.com/shopforum/diesel-discussion/394730-got-1985-300d-turbo.html

Post #99

And BTW I am really enjoying the blue 300d with its ice cold AC through the center vent provided by the nearly new everything. I eventually replaced everything except the evaporator to get it functioning properly. Now it’s perfect.

You can prop the center vent open with a stick. Better is putting a zip tie on the vacuum actuator and holding it back.

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles

I went through what you are going through on my 85 300D. To prop open the center vent pod, you can get much better access by also removing the passenger side center vent. On page 2 of this thread http://www.peachparts.com/shopforum/diesel-discussion/400609-85-300d-ac-center-vents.html , I've posted some pics of what I did.

Replacing the center vent vacuum actuator is next to impossible w/o removing the dash first. Don't waste you time to try.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Following another thread I removed the glove box liner and the right center dash vent (grasp and twist, it pops loose, hard to get back tho') , reached in and easily pushed the plastic pin out of the actuating rod, pushed the center vent flapper open and buttoned it all bck up ~ now I have lots of blessed air coming out the dash vents .

The blower comes on more frequently but still not always so I'll have to go back in and remove that blower control box and get it re capped .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better