Main air flap? Why??
 

I'me in the process of resurrecting the ACC vacuum controls in the 300D, and I'm trying to simplify things. I've got leaks just about everywhere, so I'm taking a few components out of the system. The center vent element and the recirculated air element have been disconnected and their vacuum switches plugged. I can easily close the center vents manually, and I like having recirculated air all the time. Two down, three to go. I'm keeping (replacing) the defroster and floor vent elements, so that just leaves the element for the "main air flap". What is the main air flap, and what does it do? If I don't need it, I think I'll just leave it in the open position and go with a two-circuit ACC vacuum system.

On an 84 300d it is used to control the outside air input into the system, no vaccum to the vacuum element is the closed position which does not let any outside air in. It is always in the open mode in the total ventilation mode , normal modes, economy modes, and defrost mode.

semi hijack
 

On an 85 300TD, does the yellow/black vac line that goes through firewall go to something in ACC system? I know the solid yellow goes to the driver door, and the green/yellow I believe goes to area behind ACC unit. I came here to search that when I saw this post and thought there might be a relation.
It doesn't hold a vac, and my door locks aren't working and it takes 5-10 seconds to shut off. A violent shuddering shutoff at that! :eek: Yellow line holds vac.

JimmyL , I am not sure about those lines you really need a vacuum gauge and check the vacuum pump output.

Vac pump putting out about 22whatevers. I had a bad 4 way joint. Still don't know what the yellow/black line goes to, as it still doesn't hold vac, but it doesn't affect the shutoff, which is now instant, and the door locks, which work with purpose now.
Is there a vac diagram, with colors, that shows what all this mess is on 85 models? Good grief there are 20 lines I don't have a clue about. :confused: I've looked at the vac sticky, but it isn't real specific.
Cateaux, I'm so sorry for the hijack cause it was brazen!

Main air flap: anybody.........???????

Thanks! I'll be definitely be taking that element out of the mix. Who need outside air in the Gulf South?!

Don't worry about it; I've hijacked a thread or two in my day :) . As for the black and yellow vacuum line I don't have one, so I don't know what it is for. However, I can tell you that vacuum is measured in "inches of mercury" (the notation is "Hg, as in 22"Hg).

Where is this valve located? I'm wondering if this may be part of the reason my AC isn't cold.

Take out the glove box and you'll be looking right at it. It's the easiest vacuum element to get to.