Best free improvement for the 300D W123
 

I made a modification to my '85 300D that I think is probably one of the best free mods you can make on the 300D with the automatic climate control system. I totally removed the damper door and vacuum actuator for the center vents in the dash. The dash does have to be off to make this mod but in my opinion it should have been done like this from the factory. If I want the center dash vents closed I will do it manually:) using the dash vents. You do have to make sure they work. Works great and is free:).

I took the vacuum hose that went to the center vent vacuum pod and put it straight to the 1/2 section of the defrost vacuum pod. Not sure what it's purpose is but the system works great.

Thank you! It's nice to know I'm not alone in my quest for heated air for my hands and face. I wear pants, socks and shoes when I drive, not gloves and a mask :p

I've been contemplating reversing the spring in the center vent pod since you don't have to pull the dash of the SDL to do that much. And as you say there's a lever to manually shut the center vents.

Sixto
87 300SDL

My main drive was to make sure that I can always make cold are blow out those babies. I don't worry that much about the heat. I did notice that when I want the heat or defrost and those particular damper doors open there is not that much force out of the open center dash vents and again - you can shut it off all the way with the manual shutters. The 126 is the same except for the difference in the way you shut if off.

engatwork,

can you explain a little more what you did and what your car does now after it. it sounds interesting. i just want to understand what you achieved. do you still have appropriate A/c and heat when you want them??

I simply disabled my center vents by removing the actuator and plugging the lines. Big hands = big trouble. You need to squeeze in there to get it out (without removing dash).

Now that's almost worth pulling the dash for.

I want only COLD (fresh) air coming from that vent.

I'll have to do that for my SDL. I can replace the rubber vacuum pod diaphrams at the same time.

Yes, I like warm air for my hands too, but don't you get a FFFFFFFF sound when you close up the jets?

Does this mod allow heated air to come out in the winter and A/C cooled air to come out in the summer? Like most other cars? I have never had one of these appart to see with my own eyes yet.

yes.

cool.....that is what aggrivates me most about the car....no hot or cold air from the center vents when I want it... I like to direct the other vents at the windows to keep them clear on short trips.

I wonder if this would work on my SD. And if I could achieve the same effect by plugging the vacuum line to the center pod and wiring the center vent door open?

Ahh, the joys of a "simple" 240D. No vacuum here, all manual slides. :D

Pete keep in mind that the center vacuum pod is fail shut. That means that the vacuum pod is spring loaded whereas without vacuum on it it is going to hold the damper door shut (which is what makes me want it out of there). You will physically have to disconnect the vacuum pod from the damper door and then plug the vac line.

83/300SD - I have noticed that with either the defrost open or the footwell open then the force of the air making it to the center vents is so insignificant that there is absolutely no noise at this location with them shut in heat or defrost mode.

I believe there are a few free mods that should qualify.

1: Get the boost up to spec (12-13psi)
2: Disable the EGR and clean out the intake
3: Adjust the ALDA
4: Fine tune the tranny shift points and firmness to your preference
5: Disable the seatbelt buzzer

All these are free (from cost, not labor) and will result in a fine-tuned car that you will enjoy driving even more.

by "wire open" I meant put some picture wire around the linkage and pull the door open against the spring force and then tie it down. If this could be done by sneaking a wire through the right place and not taking the dash off to do it, I'd be all for it.