where does this grey hose go? non AC 88 Gran Fury

M Body General Discussion

  1. IndieDippy

    IndieDippy Well-Known Member

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    i'm sure many of you have had to fix the HVAC hoses. i've gotten it except for one thing. where does the grey hose go? from the schematics it clearly doesn't go to the bushel the others go to but it still clearly has a crumbled piece of plastic on it. video i watched said something about a "vacuum check valve" where is that?

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  2. IndieDippy

    IndieDippy Well-Known Member

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    here is the schematic my car operates off of. the number 6 spot has a red line therefore it is sealed.

    Screenshot_2019-12-15-14-09-48 (2).png
     
  3. Trey

    Trey Well-Known Member

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    From the schematic it looks like it goes to the heater control valve, which on most cars is under the hood. It regulates the water going into the heater core, depending on whether it's heating or cooling.
     
  4. IndieDippy

    IndieDippy Well-Known Member

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    its going out to the firewall here. what does it do once its in the car is my question. i don't believe it was part of the cluster as it doesn't appear on any schematic. seems that without this piece nothing works or my heat outright doesn't work regardless of the hoses being broke. pressing buttons does absolutely nothing

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  5. lowbudget

    lowbudget Well-Known Member

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    There is a vac hose connector up under the dash. Pull the cluster and stereo. Be careful with the connector as the other vac lines will pull out. Hopefully you will just need to put it back in the connector.
     
  6. BudW

    BudW Moderator Staff Member

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    There is a “cast in place” “Y” in the vacuum hose behind the ashtray area.

    Of the two hoses going through the firewall, the black goes to intake manifold and is the only vacuum supply.
    The gray hose goes to the hot water valve under hood. The hot water valve is closed when ventilation system is “off” or in “Max A/C” mode.
    The “Y” junction is shown in this picture close to the black/pink star – but don’t remember what the hose colors are.
    Annotation 2019-12-17 172134.jpg

    The picture you have listed (post # 2, above) is from Chrysler, but it doesn’t look correct.


    Also, look for this black hose under the hood (yellow arrow).
    20161201_125857r m.jpg
    This picture is taken on driver’s side of car, behind the carburetor and looking towards the distributer. You might have to loosen the air cleaner and move aside a bit to get a good look. This black hose travels about two foot before going through the firewall. If that hose/line is cracked or broken, it will need to be fixed before vacuum reaches inside the car.
    BudW
     
  7. IndieDippy

    IndieDippy Well-Known Member

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    i think i understand now. i guess my Y fell apart and thats why the grey wire is dangling under the dash. anyone got a picture of this Y so i can see how it goes together? its getting below freezing here in MD and this is my only car so it'd be nice to finally get some heat. i have put the multi colored hoses together with wiper wire but the purpose and placement of this grey one continues to elude me.
     
  8. Ele115

    Ele115 Well-Known Member

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    I'll see if mine has the "Y" I can possibly take a photo tomorrow. I have several M's, should be no biggie if I leave myself a note to do so
     
  9. IndieDippy

    IndieDippy Well-Known Member

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    thanks. have you had this issue as well? seems common
     
  10. Ele115

    Ele115 Well-Known Member

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    I have run into this on most cars from the 60's onward. When the problem is no defrost, or weird blend air door issues etc, it's almost always a vacuum line or cracked reservoir. The old Cadillacs are a real nightmare.
     
  11. Ele115

    Ele115 Well-Known Member

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    I'll try to get a decent picture up later, I can't seem to get anything. I have where the purple and gray hose go through the firewall right by the top of the throttle cable. They come back toward the ash tray and they are clipped up behind the big plastic junk, which is why my pictures aren't coming out. I don't see a "Y", unless the white thing holding the two together behind the ashtray is, which I doubt. The big white door buzzer thing or whatever it is, is in my way. If there is a splitter, it has to be right by the dash, not near the firewall. I have about 20 mediocre photos and I don't see it, just the various plastic tubes and a few check valves and actuators. Where it goes into the engine compartment are two of them, violet and light gray. I'll be back later.
     
  12. Ele115

    Ele115 Well-Known Member

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    Keep in mind if you have the police one, you have a whole LOT of extra wires and brackets in the way. I was just reminded of that.
     
  13. IndieDippy

    IndieDippy Well-Known Member

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    mines a civie car. i see this is more difficult than i thought. i know purple goes in the multi colored cluster but the grey one eludes me still. luckily we've been having a warm week.