HVAC under-dash vacuum lines question

Interior and Electrical

  1. rcmaniac791

    rcmaniac791 Well-Known Member

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    What's up everyone, got a bit of a question here.

    I began working on the A/C in the 5th again today, and when I turned on the air, I only got airflow from the defrost, not the vents on the dash. I couldn't redirect the airflow to save my life.

    So I took out the panel under the driver side of the dash, and little green chunks of what used to be rubber fell out, and I noticed that the color-coded vacuum lines were all hanging, disconnected. I'll attach 2 pictures for a reference.

    I know that finding another green connector will be near impossible, and I'm pretty sure that I can simply re-attach the colored vacuum lines to their corresponding black line using some small pieces of rubber vacuum line, I just don't know what the order of the colored lines is in order to reconnect them properly. Does somebody have a picture of this assembly that is still in tact so I can reference that? Any other tips? Thanks.

    BTW, I did cap off the pink line, since I determined that was the vacuum signal, and I didn't want a vacuum leak.

    IMG_1176.JPG IMG_1175.JPG
     
  2. Dr Lebaron

    Dr Lebaron Well-Known Member

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    Another board


    I use vac tubing to bypass the rotted connector.
    as long as the colors go to the right ports it will work.
    The one with the x has nothing going to it.
    and a red one is on the other side of the connection going to the empty spot.


    Left to right top 3
    Brown, Yellow, Lt Green


    Left to right bottom 4
    Dark Green, Red, Purple, empty


    I pulled a perfect, non rotted complete vac system,
    from my 81 Lebaron parts car.
    I use it as a reference for the other Ms.
    I followed this for my 88 Diplomat AHB and everything works as it should.
    Vac Diagram.jpg
     
    rcmaniac791 likes this.
  3. Dr Lebaron

    Dr Lebaron Well-Known Member

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    Marty-
    3847622 is the part you need. A/C vacuum hose and connector

    includes both connectors (one at each end)

    I have it www.arizonaparts.com
     
  4. rcmaniac791

    rcmaniac791 Well-Known Member

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    This is just what I needed. Thank you!
     
  5. Rustyroger

    Rustyroger Well-Known Member

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    Subscribed so I can refer to the information here. :)

    Roger.
     
  6. Rustyroger

    Rustyroger Well-Known Member

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    My 1984 Fifth Avenue had no block connector at all, just seven vacuum line coming from the HVAC control. However thanks to the guys who contributed to this thread I got it figured out. :)
    All is still not well, I couldn't get the vents to stop blowing air in any position other than "OFF".
    So I checked out all the actuators and it turned out to be the bi-level & a-c/heat actuator is working, but the rod it operates is seized. I'm guessing it operates a door that opens and closes airflow to the vents?.
    I suspect the heater/a-c unit needs to come out to fix this, how big a job is this, or is there another way to approach the job?.

    Roger.
     
  7. Aspen500

    Aspen500 Well-Known Member

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    You are correct. The vacuum motor moves a door inside the plenum. IF your '84 is the same, or similar, to my '79 Aspen, that actuator attaches inside the plenum and it (the plenum)has to come out, then apart, to change the actuator. Should be on the left end of the plenum, near the throttle pedal. It's called the mode door actuator and switches between vents and heat/def.
    What you may want to do is, remove the nuts that hold the actuator on and see if you can pull it out. That would check if the door itself is stuck or the actuator is stuck.
    It is a big job to change. The HAVC plenum has to be removed from the car which isn't really a 10 minute job.
    If it is the actuator, the next hurdle is finding a replacement. I had a heck of a time finding a recirc door vacuum motor last year. Got it from Deconstructor Jim, who used to be on this site but stopped posting suddenly over a year ago, for some reason.
    If it turns out you need one, you can try him through his website.
    Jim's Az Parts
     
  8. Rustyroger

    Rustyroger Well-Known Member

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    Guess I'll have to bite the bullet and pull out the plenum. I already removed the screws holding the actuator, in my case it's outside the plenum, fairly easy to get to, and checked if it worked by removing and replacing the vacuum tube. the actuator itself is fine, as are all the others which is at least some good news, but the rod attached to the actuator won't move.
    Before I pull it all apart I'll try getting under the dash and trying to free the door, but hope for the best, prepare for the worst.....:rolleyes:
    Anyways, thanks for your quick reply.

    Roger.
     
    Last edited: Jan 15, 2019 at 2:46 PM
  9. Rustyroger

    Rustyroger Well-Known Member

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    I managed to free off the door without taking the plenum out. I was able to remove the defroster ducts and air vents, which gave me access to top of the post the door pivots on, a little WD40 and jiggling the post with some vise grips freed it off. :D
    So I turned my attention to the heater blender, the door was also seized but after removing the motor I was able to free it off in the same way as the other door.
    But... the motor was also seized. Nothing to lose, I pried the cover off an found everything stuck solid. The motor wouldn't turn, the sprockets taking drive from the motor to the rotating head, the head itself, all seized. Normally I'd have said forget it, I'll get another one. But I want to put the interior back together as soon as possible, so an afternoon freeing off every moving part ensued. Still, I now have a functioning air blender system again.
    Then a trip to the local DIY store for some foam draught excluder so I can put the ducting back without any leaks.

    Roger.