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  1. #26
    FEP Senior Member 4EYED85's Avatar
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    Quote Originally Posted by rock4451 View Post
    Okay, do I need to hook a ground up, too? Or is it already ground through the metal case? You're saying that 12v to either the orange or black wire should make the motor spin?....and how do you know?
    Yes, hook a ground up. One way will blow out of defroster and other way will pull air. The only reason I bring this up is I bought a blower for my car and the wires were reversed on the motor so it spun the wrong way.

  2. #27

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    When digging around in the 86 electrical and vacuum pages, I found this, and the wire colors match the colors going to my resistor Exactly.

    Why does my resistor assembly have the wire colors of the above page, but this page shows resistor wires should be different, which is out of the same book:

    Last edited by rock4451; 01-08-2014 at 12:23 PM.
    Light Regatta Blue 1986 Mustang GT 5sp - bone stock....block and rotating assembly.

  3. #28

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    Hi Sean,

    Thank you for answering my question even though you've already answered it when Kbrandt asked. My bad!

    Okay, page 78 is for the heater only, not for cars with AC and Heater. The wire colors and wiring are different and now you know the difference! You definitely have an '86 wire harness and your resistor wiring is correct for an '86. Now, When the key is in the RUN possition, the blower motor should be turning at a slow rate. At you resistor plug, check if the Orange-black wire has 12V to ground. I would attach a jumper wire to the O-Blk and the other end to any bare metal surface of the care. The blower motor should spin pretty fast. If no go, go to the AC selector switch and using a meter see if it is getting 12V power into it (the Brown-Orange wire from fuse 9) when the ignition key is in the run position. Measure between the wire and ground.

    If that's good, check the Dark blue-Light green wire on the connector attached to the AC selector switch (make sure it's atttached to the switch so we may see if the ac selector switch is good).

    If power is present there, check the DBl-LtG wire at the blower motor connector. If that has power, do a continuity check at the blower motor connector of the O-Blk wire with the fan switch on high (one lead on the O-blk wire, the other to ground). If that is good, the blower motor is shot.
    Proud owner of the one and only Friggin' Futura

  4. #29

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    I found this on Veryuseful.com, and it shows the switch terminal and resistor to both have the wires I have on my resistor, but this has to do with AC and not heat...this is confusing. Is the resistor assembly for my heater or factory AC or both?

    image hosting
    Last edited by rock4451; 01-08-2014 at 01:38 PM.
    Light Regatta Blue 1986 Mustang GT 5sp - bone stock....block and rotating assembly.

  5. #30

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    Okay, thanks for clearing that up! None of the diagrams I saw had that pointed out anywhere about the differences in heat only and heat & ac.

    So with the key in RUN, I should ground apply a ground wire (from battery or bare metal) to orange/black wire at my resistor assembly and this should cause the fan to spin pretty fast?

    If that doesn't work, check that the brown/orange wire is getting power from fuse 9 (I already checked this, and it is).

    At the blower motor connector, the dark blue/light grn wire has around 10.6 volts

    So I should check the blower motor connector of the orange & black wire (it connects to a black wire that goes to the blower motor via the connector) to make sure it's getting power? I can remember off hand that it isn't, on that connector that goes to the blower motor (DB/GRN connects to orange and ORG/BLK connects to black), the dark blue/grn is getting 10.6 volts and the orange/blk wire is showing no power. Those should both have power you're saying?
    Light Regatta Blue 1986 Mustang GT 5sp - bone stock....block and rotating assembly.

  6. #31

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    What does the little flap do above where the passengers' feet would be? What controls this? Also, how solid are the vacuum connections between the controls? Do they usually last a while or do they have to be replaced? I haven't touched anything inside the car but I don't have any vacuum connected to the manifold from the inside, although I was told I may have to connect the small line by my heater tubes to manifold vacuum. I have no intention of running A/C.
    Light Regatta Blue 1986 Mustang GT 5sp - bone stock....block and rotating assembly.

  7. #32

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    Without a vacuum connection, the system will default to the defrost position. If you want anything
    else to work, you need to connect up the vacuum. Whether or not you actually connect up the A/C
    is not relevant.

    The door you can see in the passenger's footwell controls whether the system will recirculate air
    that's inside the car, or pull in fresh air from the cowl. The servos and hoses inside the car usually
    last a very long time. My '67 and '68 both still have their originals, as do all of my Foxen.

    When your HVAC function lever is anywhere other than the bottom, and the ignition switch is on,
    you should have power on the dark blue/light green wire. The orange/black wire should read low
    resistance to ground. You should not see any voltage, or very little anyway, on that wire. When
    the fan switch is on High, it bypasses all the resistors (and the thermal fuse that's in the resistor
    assembly).

    BTW, if the blower motor connections are reversed, the blower will not suck air through the system
    ducts, it'll still blow the same direction, but with less flow. A squirrel-cage blower can only move air
    one direction, no matter which direction the motor turns.
    Cheers,
    Jeff Cook

    '85 GT Hatch, 5-speed T-Top, Eibachs, Konis, & ARE 5-Spokes ... '85 GT Vert, CFI/AOD, all factory...
    '79 Fairmont StaWag, 5.0, 62K original miles ... '04 Azure Blue 40th Anny Mach 1, 37K original miles...
    2012 F150 S-Crew 4x4 5.0 "Blue Coyote"... 65 coupe, 289 auto, Pony interior ... '67 coupe 6-cyl 4-speed ...
    '68 Vert, Mexican block 307 4-speed... '71 Datsun 510 ...
    And a 1-of-328 Deep Blue Pearl 2003 Marauder 4.6 DOHC, J-Mod, 4.10s and Lidio tune

  8. #33
    FEP Senior Member 4EYED85's Avatar
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    My bad on the direction of flow, I just knew mine was wired wrong and not pushing much air.
    I see we are back on the subject of vac., have you even made the blower comes on yet?

  9. #34

    Default 86 Mustang Heat Help!

    Good news, I think lol.

    Blower motor works good, I applied 12v to it from the battery and grounded it to the battery negative and it fired up. Turned the key on, and grounded the orange and black wire at the blower fan connector and it fired up. Now to diagnose why it doesn't work otherwise... I will report back with findings.

    There is no continuity when I probe the orange wire and a ground.
    Sean
    Light Regatta Blue 1986 Mustang GT 5sp - bone stock....block and rotating assembly.

  10. #35

    Default

    I must say I was having same problem with blower fan default to defrost only but it was my fault I changed heater core and forgot vacuum line on fire wall thanks everyone who comment big help for me sorry to thread jack

  11. #36

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    There Is continuity from orange/black at the switch and org/bk at blower connector.


    Sean
    Light Regatta Blue 1986 Mustang GT 5sp - bone stock....block and rotating assembly.

  12. #37

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    So this is the switch!


    ...and the connector!

    There is good continuity between the black wire at this connector and ground, too. How in the hell do I rig up this connection for the ground in my connector?


    Sean
    Light Regatta Blue 1986 Mustang GT 5sp - bone stock....block and rotating assembly.

  13. #38

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    Clean the connections, and tighten up the one that was loose and getting hot. Then plug it back
    in and give that one wire an extra push with some needle-nose pliers or a small screwdriver. If
    you've made it tight enough it won't fall out.

    Or you can buy a pigtail and just scavenge the connector shell to put your original terminals back
    into. Standard S-625. http://www.summitracing.com/parts/smp-s625
    Last edited by JACook; 01-08-2014 at 10:42 PM.
    Cheers,
    Jeff Cook

    '85 GT Hatch, 5-speed T-Top, Eibachs, Konis, & ARE 5-Spokes ... '85 GT Vert, CFI/AOD, all factory...
    '79 Fairmont StaWag, 5.0, 62K original miles ... '04 Azure Blue 40th Anny Mach 1, 37K original miles...
    2012 F150 S-Crew 4x4 5.0 "Blue Coyote"... 65 coupe, 289 auto, Pony interior ... '67 coupe 6-cyl 4-speed ...
    '68 Vert, Mexican block 307 4-speed... '71 Datsun 510 ...
    And a 1-of-328 Deep Blue Pearl 2003 Marauder 4.6 DOHC, J-Mod, 4.10s and Lidio tune

  14. #39

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    Inside the switch there is no continuity from the ground black terminal to ANY of the other terminals in ANY switch position. So......who has one of these switches setting around?? Lol in all seriousness, will I need an 86 specific ac and heat car switch for it to work right?


    Sean
    Light Regatta Blue 1986 Mustang GT 5sp - bone stock....block and rotating assembly.

  15. #40

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    Good! I'm Glad Mr. Cook pointed an error I made earlier: The blower motor runs when the key is turned to the run position and the HVAC function switch is not in the OFF position.

    Okay, try to do a continuity check of the fan blower switch. Use the schematic you've posted in post #29. If it doesn't show continuity, then that is your first culprit.

    Regarding the vacuum feed for the HVAC, it gets its vacuum from the plastic black vacuum tree bolted on the cowl. from the plastic vacuum tree it plugs into a one-way check valve. There are two other ports on the vacuum check valve. One goes to the HVAC and the other goes to a vacuum reservoir I call the vacuum ball.



    You can see the check valve on the shorter '84 vacuum line. The broken off vacuum line is the one that goes to the HVAC. The last port goes to the vacuum ball.



    Unfortunately, in order to access the vacuum ball, you have to get behind the RH fender liner.
    Last edited by Dean_T; 01-08-2014 at 10:51 PM.
    Proud owner of the one and only Friggin' Futura

  16. #41

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    The blower switch is common to factory A/C Mustangs from '79-'86, or any year Fairmont/Zephyr
    with factory A/C. Motorcraft YH376, or Standard HS-222
    Cheers,
    Jeff Cook

    '85 GT Hatch, 5-speed T-Top, Eibachs, Konis, & ARE 5-Spokes ... '85 GT Vert, CFI/AOD, all factory...
    '79 Fairmont StaWag, 5.0, 62K original miles ... '04 Azure Blue 40th Anny Mach 1, 37K original miles...
    2012 F150 S-Crew 4x4 5.0 "Blue Coyote"... 65 coupe, 289 auto, Pony interior ... '67 coupe 6-cyl 4-speed ...
    '68 Vert, Mexican block 307 4-speed... '71 Datsun 510 ...
    And a 1-of-328 Deep Blue Pearl 2003 Marauder 4.6 DOHC, J-Mod, 4.10s and Lidio tune

  17. #42

    Default

    Quote Originally Posted by JACook View Post
    Clean the connections, and tighten up the one that was loose and getting hot. Then plug it back
    in and give that one wire an extra push with some needle-nose pliers or a small screwdriver. If
    you've made it tight enough it won't fall out.

    Or you can buy a pigtail and just scavenge the connector shell to put your original terminals back
    into. Standard S-625. http://www.summitracing.com/parts/smp-s625
    The switch itself is toast, there is no continuity between any of the terminals no matter the selector position! I'll pick up a new one. I saw your part numbers in your below post, thanks a lot. I just want to make sure I get one that works with my specific application which I'm trusting those will work for me.

    Quote Originally Posted by Dean_T View Post
    Good! I'm Glad Mr. Cook pointed an error I made earlier: The blower motor runs when the key is turned to the run position and the HVAC function switch is not in the OFF position.

    Okay, try to do a continuity check of the fan blower switch. Use the schematic you've posted in post #29. If it doesn't show continuity, then that is your first culprit.

    Regarding the vacuum feed for the HVAC, it gets its vacuum from the plastic black vacuum tree bolted on the cowl. from the plastic vacuum tree it plugs into a one-way check valve. There are two other ports on the vacuum check valve. One goes to the HVAC and the other goes to a vacuum reservoir I call the vacuum ball.



    You can see the check valve on the shorter '84 vacuum line. The broken off vacuum line is the one that goes to the HVAC. The last port goes to the vacuum ball.



    Unfortunately, in order to access the vacuum ball, you have to get behind the RH fender liner.
    The good news is I looked under my fender apron and both of those items are there, both the ball and the hockey puck looking thing. The bad news is I have no idea where these go, and I am not running a vacuum tree in this car so I assume one of these items needs manifold vacuum? I can tee into another vacuum line, no problem if so.
    Light Regatta Blue 1986 Mustang GT 5sp - bone stock....block and rotating assembly.

  18. #43

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    Yes, manifold vacuum should be fine. The other vacuum reservoir (I call it the tuna can just because of its general shape) is for the TAD/TAB solenoids. There is a vacuum hose bundle which I think comes off from under the upper intake and feeds multiple items relating to emission controls like air injection pump dump/diverter valves, EGR valve, a bunch of other things I fergit...
    Proud owner of the one and only Friggin' Futura

  19. #44

    Default

    Thanks so much for your help, and JAcook, and everyone else who is taking the time to respond to this thread. It helped me find the switch as the culprit of my problem and it would have probably taken a lot of curse words and hair pulling out otherwise.

    Okay, so in order for my controls to work in my car regarding which vents and airways can have air blown out of them, I need to attach the small vacuum line that comes in through the firewall by my A/C tubes to manifold vacuum? Where does the ball's line connect to? I'm not running EGR or any emissions stuff so would I even need the tuna can?
    Light Regatta Blue 1986 Mustang GT 5sp - bone stock....block and rotating assembly.

  20. #45

    Default

    Nevermind my question, Dean, I saw your explanation when I re-read your response with pictures. Thanks.


    Sean
    Light Regatta Blue 1986 Mustang GT 5sp - bone stock....block and rotating assembly.

  21. #46

    Default

    Alright, one last clarification while I have you.

    Manifold vacuum goes to a check valve (I can buy a generic one-way check valve almost anywhere it seems) and the check valve tees off into 2 lines, one of those lines goes to the ball in my inner fender, and the other connects to HVAC controls. Where does it connect to these controls? Is that the small line that comes out by the A/C tubes or is there another location? This should be all I need to know! I appreciate it.
    Light Regatta Blue 1986 Mustang GT 5sp - bone stock....block and rotating assembly.

  22. #47

    Default

    After doing some digging, I have my answer. The small vacuum line that comes through by my unused AC lines is the one that needs to be connected for HVAC controls.
    Light Regatta Blue 1986 Mustang GT 5sp - bone stock....block and rotating assembly.

  23. #48

    Default

    Glad you've solved your problem. I get home rather late so response time isn't so good.
    Proud owner of the one and only Friggin' Futura

  24. #49

    Default

    Well turns out I have a broken off line, it comes through by the ac lines into the engine bay but it's broken shortly after. Anyone have advice where to get small flexible hose that would work? I mean it's pretty damn thin!


    Sean
    Light Regatta Blue 1986 Mustang GT 5sp - bone stock....block and rotating assembly.

  25. #50

    Default

    You can replace the plastic line with 5/64" diameter windshield washer hose, using splice fittings
    to adapt the hose to the connections after removing the remains of the plastic tubing from them.
    Or if the tubing isn't broken off flush, just push the hose over the end of what's there.
    Last edited by JACook; 01-10-2014 at 02:34 AM.
    Cheers,
    Jeff Cook

    '85 GT Hatch, 5-speed T-Top, Eibachs, Konis, & ARE 5-Spokes ... '85 GT Vert, CFI/AOD, all factory...
    '79 Fairmont StaWag, 5.0, 62K original miles ... '04 Azure Blue 40th Anny Mach 1, 37K original miles...
    2012 F150 S-Crew 4x4 5.0 "Blue Coyote"... 65 coupe, 289 auto, Pony interior ... '67 coupe 6-cyl 4-speed ...
    '68 Vert, Mexican block 307 4-speed... '71 Datsun 510 ...
    And a 1-of-328 Deep Blue Pearl 2003 Marauder 4.6 DOHC, J-Mod, 4.10s and Lidio tune

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