Replacing A/C vacuum pods
 

I have replaced all the vacuum pods on my 84 300SD but one. It is the one on the very top in the center. It looks like I will have to take the air box apart to get to the attaching posts with the sheet metal nuts. It is such a hard job I wanted to ask those that have done it before if i need to do that. I have the dash off. It is the pod on the rectangle frame with screws. Thanks for your help.

If you mean the one mounted in a plastic frame held by sheet metal screws, that is a single diaphragm pod. I'd leave it unless the dash was coming out for some other reason or I wanted everything finished at the same time. There are several pods that require the dash to be pulled or at least moved back.

not sure if the SD is the same as a D, but for the center vent on a D you can get it with a little patience without removing the dash.

for a 300D I did this:

you will need 3 replacement metal locking washers as they do not come with the center vacuum pod

1 remove glove box liner
2 remove instrument cluster
3 remove rubber center vent duct
4 unplug CC air sensor and remove sensor
5 remove 2 round ducts from dash by gently turning from the back to release the ring
6 reach in with wire cutters and snip the edge of the washers, they will then open and come right off
7 remove pin on actuator rod
8 remove pod
9 rebuild pod or discard if you have a new one

reassemble in reverse order, dont forget the rubber washer under the metal locking washers

Speaking from W123 experience, another option is to disassemble the pod in situ, leaving the black half attached at the speednuts. Take off the pink half, detatch the actuator arm and slide it out of the black housing along with the torn diaphragm and spring. Reassemble in place, using a Mytivac to suck it all together once you can get the diaphragm to seal against the pink half of the pod.

yep this works too :) but requires a little more patience

I Did it.
 

After Roy sent me some info and once I was sure of which way to proceed, success. I rebuilt in place. Now I can put the dash back on.
Thanks everyone.