Hvac Is Stuck On Floor Vent Setting

Discussion in 'Fox 5.0 Mustang Tech' started by Aftrbrnr, Jun 24, 2013.


  1. Aftrbrnr

    Aftrbrnr Whitey cashier gave me the wrong change at the sup Founding Member

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    My '92 LX is stuck on "floor", could it be as simple as a fuse or the motor that controls the vent direction?
     
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  2. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    no, i believe its vacuum actuated so likely a vacuum line busted behind the contrls or smething blocking the dampers operation
     
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  3. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Lack of vacuum to operate the vacuum powered actuators...

    Diagram courtesy of Tmoss & Stang&2birds

    [​IMG]

    See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

    Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
    http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

    Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
    http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

    Ignition switch wiring
    http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

    Fuel, alternator, A/C and ignition wiring
    http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif


    Vacuum diagram 89-93 Mustangs
    http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

    HVAC vacuum diagram
    http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

    TFI module differences & pin out
    http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

    Fuse box layout
    http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

    87-92 power window wiring
    http://www.veryuseful.com/mustang/tech/engine/images/mustang87-92 PowerWindowWiring.gif

    93 power window wiring
    http://www.veryuseful.com/mustang/tech/engine/images/mustang93PowerWindows.gif
     
    #3
    SoFlStang likes this.
  4. Mustang5L5

    Mustang5L5 Car used in adult film "Highway Gangbang-InDaButt" SN Certified Technician Founding Member

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    Doing any work under the dash recently??

    On the driver's side center of the dash there is a single vacuum line buried under the dash that plugs into the HVAC box. If this slips off or breaks....you get the symptoms you describe
     
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  5. SoFlStang

    SoFlStang Member

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    jrichker, Thanks for the above information, this is the next project I am looking at tackling on mine.

    I do have a question, and hope this isn't a thread hijack. I noticed on the diagram, there is an outside recirculate door. On my car, I have some rust inside the cowl, which causes water to pour into the passenger floor when it rains real heavy. Right now I have the cowl temporarily sealed off, as this is beyond my repair abilities. Would it be possible to close the recirculate door and when I install the new A/C system, just run it with the door closed, pulling air from inside the car? Just want to see if it can be done before I purchase the A/C parts that the previous owner decided to remove.
     
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  6. MikeH686

    MikeH686 Mine is only two inches though.

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    The door will not seal out all of the water but the eay you keep out the outdoor air is keep it on max ac
     
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  7. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    The fix for rust in the cowl area isn't that hard since it isn't easily visible with the cowl cover on. You will probably want to wait until you get ready to do the A/C installation work. It will make it easier to get to the area underneath the cowl if it is necessary to do some rust treatment/prevention in that area..

    Remove the wiper blades & cowl cover; use a wire brush in a drill or similar tool to remove all the rust you can get to. Then visit http://www.eastwood.com/paints/rust-solutions.html and choose a rust treatment product suitable for the type and amount of rust you have left. See http://www.eastwood.com/tech-library and check out the tech documents they have on rust removal & prevention to help you select the right product. Clean the area with a rag wet with acetone, and let it dry. Then apply the rust treatment according to directions, and let it dry/harden. Make sure all the rust is removed or treated, because rusting is an electrochemical process that happens as long as there is metal and an electrolyte like water or moisture.

    Next get a fiberglass repair kit: It will have fiberglass cloth, resin and hardener. Home Depot, Lowes, & Ace hardware will have the kit, and so will Eastwood. Make a paper template of the area that had the rusted out section. Use the template as a guide to cut the fiberglass cloth in a shape that will cover the rusted area. If you have a large hole, use 1/4" square mesh chicken wire over the hole to support the fiberglass cloth. Some Pop Rivets can be used to secure the chicken wire in place so that it stays put when you do the next steps. Mix up a small amount of the resin/hardener in a throw away type container. Clean, dry plastic water or soda bottles are a perfect choice if you cut them in half and use the flat bottomed part as your mixing pot. Use a throwaway paint brush to coat the cowl area in the shape of the patch with the resin mix/ and extend it about 1” beyond the patch area. Lay down the fiberglass patch you cut and do your best to smooth it out and make it lay flat. While the first coat of resin mix is still wet, use the brush to apply another layer of resin mix, again, smooth out the fiberglass cloth as best you can. Let the whole thing dry/harden, it will take an hour or more depending on the temperature of the car body and the air temperature. Do your best to sand off the high spots in the hardened resin, and clean up the sanding residue. Cut another piece of fiberglass cloth in the shape of your paper template, but cut it so that the weave of the cloth is at a 45° angle to the weave of the first layer of cloth. Wipe the area down with a clean cloth and apply some more resin/hardener mix. Lay the cloth down and apply another coat of resin mix, smoothing the fiberglass cloth. Let it dry/ harden overnight, then sand off the high spots in the hardened resin, and clean up the sanding residue. Apply body filler to the patched area to level and smooth the whole area. Prime and paint to cover it up, matching aerosol spray cans of paint can be bought from auto paint and body supply stores if you bring your VIN code with you. See http://www.google.com/search?source...i22i30.0.0.2.94529963...........0.Vmea0EGbQPc for your choice of vendors and products.

    Put the cowl cover and wipers back on and you are done. If you were Mr. Neatfreak and did a good job, the work won’t be noticeable under the cowl cover.
     
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  8. SoFlStang

    SoFlStang Member

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    Thanks jrichker for the info. When I took the grated cowl cover off, I can see the hole the rust has made, but its out of reach. The raised lip where the hvac system gets its air from is what is rusted. Is there another way to get into there? If I just seal the cowl, will this cause the A/C not to function on MAX A/C since it cannot draw any air from the cowel? I have a feeling to repair the damage I can see from the cowl opening, I need to open the actual cowl and if thats the case, I would like to wait on that big of a project. Its really hot down here, so I would like to put some A/C in, but don't want to order the new A/C kit if its not gonna work until I fix the cowl. Hope that makes some sense.
     
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  9. 7991LXnSHO

    7991LXnSHO Well-Known Member

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    I think max ac is like most cars. It is recirculate mode.
     
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  10. f8tlfiveo

    f8tlfiveo My wife likes my spool and blow-off valve.

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    Yes I believe you are right
     
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