Hi All,

I lost flow through my center vents on my 1982 300SD. I read SD Blue's text description of how to go in through the ACC panel above the radio and install the vacuum pod through the vent port. Thank you. I went ahead and did it and I decided to document it for people who would like to attempt this job. It took about five hours with cleanup. This included having to take apart the kick panel a second time to find the vacuum line I accidentally knocked off during reassembly.

Ok, so lets do this. First you need to determine which pod is bad. Remove the passenger side kick panel and the panel on the tunnel. You will see the solenoid valves. This is a great place to test for pod leaks.



Get out your mityvac and start pumping down the lines on the solenoids leading to the pods. This diagram will help.



I determined that my valves were ok by powering them with a 12V power supply and pumping on them with the mityvac to see them open and close under vacuum. Vacuuming the lines on the solenoid outputs helps you isolate the problem pods. Most of mine were still good. The recirc double pod behind the glove box was bad and the center nozzle one was bad.



Just vacuum on the individual lines and see which ones hold vacuum.

I isolated the problem to pod 40. This pod handles the "center nozzle". Thanks to SD Blue I learned that I could get to this pod without too much work. As he said, "remove passenger side kick panel, tunnel panel, ash tray, radio and ACC panel. " Good stuff. So I'll show that here.



Ash tray comes out with two little screws underneath.

My radio pulls with two hacksaw blades to press down the little locks.



This exposes two little screws that hold the ACC panel in.



Pull the ACC panel slightly out and down at the same time after removing the two screws.



You should have something that looks like this. You can see the little pink pod in the upper right corner of the ACC cavity. At this point do as SD Blue suggests and stuff rags in the cavity below. You may drop things down there.



Here's a closer look at what you will have to pull out.



You'll need to pull a center vent louvre to get access to the pod.



They release with little catches on each side. Make sure to aim the louvre down to get it out. It took me awhile to figure this out. I forced it and it popped into a dozen little fins and gears. I spent a few minutes piecing it back together.

Release the pins. Aim it down before pulling.



Carefully unroll the rubber duct around the center vent. You'll be able to get a straight shot at the pod with a 1/4" drive socket with a long extension through this hole.



And this is what you'll see. There are four screws you need to remove.



Ok. I lied. it isn't a perfectly straight shot. Some will have to be removed from the ACC hole too. They are indeed 5.5mm like SD Blue said. But I jimmy jacked them with a 7/32" socket. It fit well enough. I also used a wobble head socket.



From under the dash you can see the hooked end of the pod on the flap. You'll need to free this with some kind of long nosed plier or screwdriver. I'm looking into a duct opening in the airbox in the passenger side foot well.




Ok, you freed the hook and how you need to wiggle the pod out. I snaked mine out this way. It was like a puzzle getting it rotated out.



And here it is. You'll need to install your new pod in the rectangular shell. Do not lose the starlock washers. They are hard to source in 4mm shaft diameter.



So now you have to reassemble. Reassembly is the reverse of assembly. Not so fast. Getting that little hook on the flap is a doozy. I found it useful to use some small wood dowels to form a hook, hold the door closed and pull the pod's hook into the clip on the flap. Here are the tools I made/used. I just ran a nail through one of the dowels to make a hook. I used a flexible gooseneck light to illuminate the evaporator box from the inside so I could see what I was doing. It is a slim inspection light. Shown on the right. I just made a hook out of it and hung it over the lip of the opening. You will need all the hands you have to work the flap and pod lever into position. Also useful was putting my mityvac on the pod and moving the actuator to a friendly position where it was easy to slip the hook into the hole on the flap. That extra degree of adjustability made it possible to get it hooked in without too much fuss.



And that's pretty much it. Now put it all back together.

Enjoy! Thank you SD Blue!!!

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

Great write up and glad to help! As you found out, it's not a bad job but it does take a bit of time. The key is get comfortably situated and take your time. Hopefully, the repair will last another 20 years!

This is such great timing. I'm planning to tackle this on my 350SDL soon.

Thanks so much for sharing!

Great write up.

I have done it that way once, lot of hassle. I reach through the driver foot flap to disconnect the pod's hook from the door within the box...this leaves the base of the old pod still attached to the HVAC box. Sounds hard, it is not.

Toss on a replacement diaphragm and hook it back up.

Nice write up and I am jealous of those MB Tex seats.

__________________
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

Great write up and pictures...Took me about 4 hours thanks to the excellent instructions. One small point that may help others is aligning the plastic collar on the flap that the vacuum arm goes into before trying to put the end of the arm through it.
If you look at the arm of the pod that is mounted just on the outside of the airbox (defrost I think) for reference you will see what I mean. I had it hooked in the flap but had to remove it to turn the collar so I could get it completely seated.

I had a couple general questions about these pods. Is there any acceptable amount of leak down on them? I have one that slowly leaks down vacuum after about 5 minutes. Its the one by the gas pedal.
Also, in following the instructions in the FSM on testing the fresh air pods (behind the glovebox) I discovered that they don't hold vacuum unless the other line that goes to them is plugged. For example if I pull the bottom green blue line off the lowest of the switchover valves and vacuum it out it doesn't hold unless I plug the red one above it that goes to the same circuit. Is this normal?

Any help would be much appreciated and thanks again for the great directions.

Very clever. Yes, it makes sense and you don't have to unscrew that base. Where do you get the diaphragm? The link posted years ago here is dead.

The Tex seats are replacements from World Upholstery. There are cheaper options now. There is a current thread with a member who got leather for $300 for the front.

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

Thanks for mentioning this. You know what? I did have trouble with that inserts orientation. I just thought nobody was as dumb as me so I didn't bother mentioning it. . Yep, I had to rotate it around with a screwdriver before the hook would seat.

As for your behind the glove box pods I would say what you are seeing is not normal. I have new and old ones (old are bad) on the bench and the good ones hold vacuum on the red and green/blue ports. I'm testing directly on the pod. I got away with one bad pod for a long time because there are two pods. The flap just worked slowly. Also there is a big spring on the red side that works in the green side's favor.

I think the vacuum pump can keep up with a leak rate that drains the mityvac in 5min. Remember there isn't much volume in the mityvac. The car has the pump and the reservoir tank. But it does sound like you have a pinhole in there. Based on my experience with these pods little leaks lead to big leaks as time goes by. If it works you can keep using it till it doesn't. You won't have far to look when it comes time.

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

Hey, I just went down to the garage and played with a good double action pod from behind the glove box. Yes, it holds vacuum on the green and red side. If I had to guess you have at least two punctured diaphragms on one or more of the pods. You are pulling air through the green circuit and it is leaking in through the red circuit because both diaphragms in one or both pods have holes. I guess the red circuit would normally be plugged if you left it on the switchover valve and the car was shut down. But that wouldn't do any good because the pod actuator won't move if you pull on the green circuit and it just connects right through a series of punctures to the red side and clear back to the red switchover valve.

Sounds like it's time to pull both pods and check them independently. Good luck.

Btw - on the 1982, one of the recirculated air pods on the back of the glove box 0008003775 is no longer available from MBZ/Behr. These have the three teets and starlock nuts on the back. If you're lucky you'll have the later ones with the bayonet mount. I had to "make" one out of a 0008003675 by removing the little metal arm from my old one and riveting it to the new one. I think I had to also change the orientation of the green housing relative to the pink housing.

Things like this are making me realize I need to think of a future without this car.

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

Thanks for the info, I was worried they were both shot. I took them out and they are both messed up in the same way, plug one port and the other holds vacuum. Fortunately they seem to be the newer design. So time to order new ones...Yeaaaa. I think I'm just gonna replace the rest of them.