I took my 84' 300D to a old Benz specialist to try to figure out why my center vents didn't blow out air when the a/c is on. He was like 99% certain that the problem was within the climate control module. So I bought a rebuilt one from autohaus and eagerly installed it. Nothing changed! Damn!!! So at this point I'm not sure what the problem is. It could be a vacuum switch-over issue, or something which is bound to be expensive. I want my a/c to work the way it's supposed to! I don't know how much I'm willing to pour into this car to find out but the problem bugs me to no end! FYI, it only blows cold air out the defrost and side vents. Has anyone else trouble-shot this problem before?
I would imagine the center vent flap controls the airflow on the center vents and it's vacuum actuated. The actuator is near the dash surface so it's exposed to heat. My idea is the rubber diaphragm tears after a while not unlike those ones buried deep in the dash.
Believe that on cold air with compressor on (middle button) the center vents should blow air, but on warm/heating mode, they don't.
That job requires dash removal. Though, instead of replacing the actuator every few years, you can disable it, and remove the center vent door. You can control center air flow by just twisting the vents, and never have to worry about that pesky actuator going out on you again. Read up on it here. http://mbca.cartama.net/showthread.php?t=9817
__________________
1981 300SD DB881 ext./code #236 leather int. aka: thistle green ext./olive int.
1982 300D, DB877 ext./code #135 mb-tex int. aka: petrol green ext./creme int.
Removing the center vent door also requires removal of the dash. Only solution is to disconnect both vacuum lines that go to the actuator, pry the actuator open using the small tab on the side of the flap's axis, and loop the vacuum lines together so there's no leak. As you can see without removing the dash it's a tight squeeze...done this to my car even before Engatwork did it and it's been great.
I've seen several of the clips that hold the actuator arm to the air flap go missing. The actuator still works, but nothing is connecting it to the air flap. Pull your glove box out and see if you can see if the actuator is actually working or not. If the clip is broken, someone with really small hands may be able to replace it without removing the dash,buts its a PITA.
Jamie
__________________
But then again, I could be wrong.........
Where is everyone? Find out here (and let everyone know where you are, too)...
Yep, I guess that proceedure comes next if repairs end up not becoming cost-effective. The modification still allows air to blow through the defrost vents full-time as well doesn't it? That is a minus because the windshield is hot from the sun and that decreases the effectiveness of the a/c. I'm making a big deal about this because I like driving out to Arizona to see my brother but last trip was uncomfortable. I don't want to drive anything other than MY BENZ! While I'm at home I use my car for work and often have my Golden Retriever "Maggie" in the car with me. In the summer it can get hot where I work so it's nce for both of us.
I guess it's time for "step II". I'll at least take the glove box out and have a look.
Thanks for the help and I'll let you all know if I find anything interesting.
I had the same issue and went the route of pulling the dash. There's a guy on eBay that sells a video for pulling the dash and installing a new diaphram. He also sells the diaphram and a tool for installing. Believe the video and parts were 30 dollars. Made the job easier and saved a bunch of time and aggravation knowing where the bolts were and what to take apart in what sequence to get the dash out. Took about 2 hours to pull taking my time. Did not think that was bad for a first time through.
My problem was that the bolt and nut attaching the actuator to the air flap had dropped off. I assume the vibration of the diesel contributed to the nut shaking off. If you choose to repair vice hard wire the flap, install a bolt with a nut that has the plastic thread. That should do a better job withstanding the diesel vibration. Good luck.
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.
Linear Mode
