I have 'renovated' my instrument cluster and found this open duct.
Does anyone know what branch goes into this open duct exit? And where does this missing branch end up?
Could it be that this connector has to be plugged?

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see that eye ball vent to the right of your picture ?.......

Right side? Are you looking at it upside down?

Oh, wait, you're viewing a pic on the internet from Australia... Now it makes sense.

The vent is on the left of the picture for us in the properly oriented hemisphere...

Thanks for the responses.
Unfortunately NO.
This open duct does not lead to the eyeball vent lower left side.
The main duct where the open branch is tapping into is leading to the eyeball.
Is there any drawing of the duct system for the 109?
Martin

It does look like it goes to the "Eyeball" vent. It should have 2 sources IIRC - one for heat/AC, and one for fresh air.

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

Thanks Tomguy,

I need to take a picture from the eyeball. Eyeball is connected to the boxy duct in the back of the open branch in the picture.
This is for the heater fan air.
Then there is a lever to the left of the left eyeball and this one operates a flap inside the duct which opens to the outside air directly.

The AC fan however doesn't reach the driver side eyeball...while it reaches the middle outlets and the right eyeball. I find this weird because I'd love to have AC on the driver side.

There should be a flexible duct/hose that runs from that connector, behind the instrument cluster and down to another connecter on the side of the A/C vent duct housing. That other connector is underneath the dash on the drivers side of the car. You will probably have to get down on your back on the drivers side floor to even see the other connector.

That flexible duct was also missing on my car. The correct size duct is not available from benz, so I had to find another source. I used a place called nostalgic air parts. Here is a link that might help.

Duct Hose sold by the foot

John

hi John,
what you are saying is logical...makes sense that this side connects to the AC core in the middle.
Is this a 1 1/2" duct? I'll crawl underneath and see if I can find the connector in the middle.
Martin

I used the 1 1/2 inch hose as the 2 inch has was way too big. It was very close to the right size, but just a touch too small. I was able to warm then end of the hose in hot water and that softened it up enough to allow me to fit the hose over the connector. That allowed the hose to fit tightly on the connecter without the use of tape to hold it on.

John

Hi John,
that sounds great!
I'll try and order a couple feet of this 1 1/2" hose.
With this hose the AC fan should blow cold air right from the left eyeball outlet?
Martin

Hi John

I found the other side.
Here is a picture of the 'other side' the AC core in the middle where the hose should connect to. The picture is taken from the driver door looking at the AC core. The upper left is the steering column.
The outer diameter of the airduct connector is 42mm or around 1 5/8 inch.
Question is if the 1 1/2" duct would fit? You said you could make it work?
I guess that the other duct left of the instrument cluster (I can't get to this one any more with the cluster installed) has the same 42mm?

The other question I had was the big rectangle flap opening left of the open round 42mm duct. It is half covered by the steering columns in the picture. Is this flap (it is operated by one of the 4 heater levers on the middle upper dash) having a hose to somewhere or is it dumping air just next to the steering columns...which is odd.
I see a screw and a piece of broken plastic (at lower left corner of flap opening)...so could it be that there is a plastic part sitting on the flap opening?

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Here's some threads and pics to help:

M-100 Message Board - Driver Side - Under Dash Covering

M-100 Message Board - Heater Levers Please Help!!

M-100 Message Board - SA 55875 HD Heatexchanger

Attached Files

W109 Heating and Ventilation.pdf (71.9 KB, 118 views)

__________________
All the best,

J. P. Mose
1968 250SL
1970 280SE 3.5 Cabrio
1987 560SL
1990 560SEL

The 1 1/2 inch diameter hose i bought from nostalgic air parts is a circular wire renenforced hose with a PVC plastic covering. I was able to stretch the ends out a small bit, which allowed the hose to fit over the slightly larger connector.

On the heater box, there should be a plastic air diverter over the opening that diverts the airflow down towards the floor. It looks as if the diverter on your heater box has been broken off. If you look at the PDF file that JP posted, it shows an exploded parts view of the heater box. The air diverter i am refering to is part 18.

John

Thanks JP!
I don't think I am going into the ventilation and heater core...I need to get the AC going primarily. Or do you think it is obvious if I am at the evaporator to look at the heating?

Thanks John.
I'll order the 1 1/2" hose and I ma trying to get #18. This part seems to be relatively small, an angled piece that just covers the one corner where I found the broken off piece?
I also saw that these flaps are not closing with a seal. There are open gaps around the flaps or is there some rubber missing in my car?
Not that I wanted to take this heater core apart necessarily. I have done it on my 126...which was a pain.
Martin