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Thread: 86 gt ac / hvac

  1. #26
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    My guess the temperature cable probably operates the same as ac/non-ac cars. The cable goes over to the hvac box blend door just to the right of the radio. There may be something to lock out the ac when on heat.

    The other cable should be the one to control things. My guess defrost is all the way up. Floor is the middle and vent is pretty much down. Add in a little more distance to ac and it will engage the ac compressor. Vent and ac should be the same output with the compressor not running. You do not need the system charged to get the levers working correctly. Maybe the cable is out of adjustment or it is more complicated than stated.

    Let me see if I can find something in the service manual. The evtm does not cover dealer installed ac from what I recall.
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  2. #27

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    Quote Originally Posted by wraithracing View Post
    Agree that IF your control unit is all cable operated, then the vacuum will not be needed. Maybe it's me, but I can only see one cable lever on your control unit. It may just be the angle and/or I am just missing it. The temperature lever should be cable operated to my knowledge, so if your control unit is ALL mechanical there should be two cables going from the control unit to the HVAC box. IS that CORRECT?

    If you do have two cables, then you need to verify that the cables are actually functioning as intended and are going thru a full range of motion. That will require at least looking up under the dash at the cable on the HVAC box to see that the cable is moving a door/lever/etc. of some kind. I believe I have one parts car that was Dealer/Aftermarket A/C and I might be able to get decent pictures of the HVAC box without the dash in the way tomorrow if that helps to determine where the cables actually go to.

    Yes! those photos would not hurt!

    Other than the selector for the air position, the temperature is on the left. I’d have to pull it again to see as I can not remember but I KNOW the temperature lever works as I can feel the air difference cold and hot

  3. #28

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    Quote Originally Posted by KevinK View Post
    My guess the temperature cable probably operates the same as ac/non-ac cars. The cable goes over to the hvac box blend door just to the right of the radio. There may be something to lock out the ac when on heat.

    The other cable should be the one to control things. My guess defrost is all the way up. Floor is the middle and vent is pretty much down. Add in a little more distance to ac and it will engage the ac compressor. Vent and ac should be the same output with the compressor not running. You do not need the system charged to get the levers working correctly. Maybe the cable is out of adjustment or it is more complicated than stated.

    Let me see if I can find something in the service manual. The evtm does not cover dealer installed ac from what I recall.
    yep the temp is on the left and it works as the temp changes fine.

    I enhanced the HVAC controls pic. Top is defrost which works. Down one is floor. Down another is vent which is like max floor and then AC is at bottom. In the second photo I attached I edited it to show that when I push the lever down to ac the notch in red connects with the green “hook” part and pushes it in which i would assume activates Name:  A8DC0C57-F3AA-47F2-AABE-105C52E7AFB0.jpg
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Size:  46.8 KBthe AC once it is charged up. Maybe I’ll try to pop the radio out and see if that gives me access to the blend door.

  4. #29

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    Just a thought as well.

    after reading a topic on here about ‘85 Mustang radio removal, I saw a lot of talk about the HVAC duct etc being in the way. I’m willing to say that when the last owner installed the aftermarket stereo, I want to say something was knocked loose or is cramped wrong. I’ll go see now

  5. #30
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    The blend door is usually directly behind the glove box but closer to the radio. It has to be in between the heater core and the evap. Core. Look for where the lines exit to get a perspective.

    The green hook is the ac compressor engage switch.
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  6. #31

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    Quote Originally Posted by KevinK View Post
    The blend door is usually directly behind the glove box but closer to the radio. It has to be in between the heater core and the evap. Core. Look for where the lines exit to get a perspective.

    The green hook is the ac compressor engage switch.
    you were right about the manual control.

    I video’d it’s movements from under the dash - these cars are really cramped but I was able to see the rotating base of the blend door move. See video.

    As far as accessing the door and checking the alignment is another story. Not sure.

    https://youtu.be/RRmPSdvbEHs

  7. #32
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    I checked the 1985 service manual. There is no mention of the dealer installed ac. I’ll check the parts book next.
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  8. #33

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    Quote Originally Posted by KevinK View Post
    I checked the 1985 service manual. There is no mention of the dealer installed ac. I’ll check the parts book next.

    I appreciate it.

    ill try to go through the glove box again see if i have more room to work

  9. #34
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    Ok, I checked the parts book. The info is limited and cryptic.

    Under the hood, there are a few versions of dealer installed ac. Most of them seem to date back to v belts which I believe is 79-84. That was probably the biggest market time wise. None of the pictures match up to your set up. The part numbers are generic so they may still ID the correct part. Things under the hood are generic for these kits. Compressors are by engine, hoses are cut to fit and condensers are universal to the dealer installed kits. The factory 3.8 in the 83-86 Tbird did seem to use a similar compressor. Likely this was for the serptine belt which was about 85 and up on the mustang. That might explain why the old v belt kits did not apply to your mustang.

    In the dash is another story. I can only surmise what happened there. My guess is they used the existing heater box and added the evap core with an add on box. A closer look suggests a piggy back box with its own blower put along side the heater box. Ok so this makes sense. Heater only used the 2 outer dash vents. Dealer ac added 2 Center vents dedicated to ac only. This means no control cables are needed for ac. And of course no vacuum supply needed.

    There were a couple of versions of dealer ac with the early ones having the ac controls in the actual vent facing the driver. There are about 3 pages in the parts book to support this.

    It looks like your hvac controls should be basic heater controls but the added and ac enable switch to what used to be the heater off position. With the ac enable bypassed, you should be able to turn on the heat and the ac at the same time as they are 2 separate systems.
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    14 Mustang CS/GT, 15 F150 FTX Tuscany, 16 F250 Crewcab, 67 Tbird 47K miles

  10. #35

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    Quote Originally Posted by KevinK View Post
    Ok, I checked the parts book. The info is limited and cryptic.

    Under the hood, there are a few versions of dealer installed ac. Most of them seem to date back to v belts which I believe is 79-84. That was probably the biggest market time wise. None of the pictures match up to your set up. The part numbers are generic so they may still ID the correct part. Things under the hood are generic for these kits. Compressors are by engine, hoses are cut to fit and condensers are universal to the dealer installed kits. The factory 3.8 in the 83-86 Tbird did seem to use a similar compressor. Likely this was for the serptine belt which was about 85 and up on the mustang. That might explain why the old v belt kits did not apply to your mustang.

    In the dash is another story. I can only surmise what happened there. My guess is they used the existing heater box and added the evap core with an add on box. A closer look suggests a piggy back box with its own blower put along side the heater box. Ok so this makes sense. Heater only used the 2 outer dash vents. Dealer ac added 2 Center vents dedicated to ac only. This means no control cables are needed for ac. And of course no vacuum supply needed.

    There were a couple of versions of dealer ac with the early ones having the ac controls in the actual vent facing the driver. There are about 3 pages in the parts book to support this.

    It looks like your hvac controls should be basic heater controls but the added and ac enable switch to what used to be the heater off position. With the ac enable bypassed, you should be able to turn on the heat and the ac at the same time as they are 2 separate systems.
    Awesome! Great Information!

    Ill try to remove the glove box and the panel above the glove box to see if that gives me access to the blend door.

    I saw when I shined my light into the passenger side left vent, that it had nasty brown foam “blocking” it. The other 3 vents you can see clearly down the ribbed tubing. Is this normal? Coincidently I saw a random tube hanging down behind the dash that resembles the ribbed tubing for the vent �� I’ll take a photo later and give an update when i take that panel above the glove box off.

  11. #36

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    I’m going to dive into the dash today. I finally took a photo of the vent foam. Please tell me what you think.

    first is the passenger seat, left dash vent. Second is what all the other vents look like. Third photo is the ribbed tubing I found hanging behind the center dash behind radio. It is inactive - nothing blows from it. Fourth photo is some sort of drain tube I found under the passenger side dash. I don’t think it should just drain into the carpet if it is a drain tube

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    Last edited by wraithracing; 03-11-2019 at 02:34 PM. Reason: Fix Pictures

  12. #37
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    I corrected your pictures to try and help others view them without throwing their necks out or having to rotate their computer screens.

    First picture, the foam could have been placed there by the P.O. to force more air to to the other vents to improve the airflow to those vents. That would be my first guess.

    Second picture looks just like a normal setup except the Factory A/C cars use a formed hard plastic tube rather than the flexible tube you have.

    Third picture, it would not surprise me if that flexible duct is supposed to hook up to the tube there just above the floor. I might be wrong as I don't have a NON A/C unit to look at, but that would be my guess. That might be floor heater tube, but that is much bigger and different than the Factory A/C heater vents at the floor.

    Fourth picture, the drain definitely should not be inside the car. There will be condensation coming off the Evaporator core when the A/C if operating properly, therefore that water has to drain somewhere. I would bet there is either a hole in the floor or firewall that the hose in question fits into.

    My guess at this point is the previous owner got in there to fix the A/C, got confused/frustrated and gave up. Leaving parts disconnected and/or not connected properly. At this point, if it were mine, I would pull the dash at least far enough out of the way to get to the unit behind the dash to verify what is and what isn't connected, blocked off, broken, etc. Otherwise I think you may be chasing your own tail here with the whole situation. Good Luck!
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  13. #38
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    Here are some pictures of a Dealer installed unit out of the car. The smaller unit is the A/C. The larger unit is the stock heater assembly.No heater core in it.
    The heater unit attaches to the firewall as factory installed, and the A/C unit sits above and the heater unit and behind the dash. There is one flex hose missing that goes on the right side of the A/C unit and attaches to the right vent on the passenger side of the dash. The small square hole in the A/C box goes to the passenger side of the dash by the HVAC controls.
    The two hoses tied together go through the firewall for the drain.
    The last two pictures are of the back side of the HVAC control.
    Attached Images Attached Images      

  14. #39

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    Quote Originally Posted by wraithracing View Post
    I corrected your pictures to try and help others view them without throwing their necks out or having to rotate their computer screens.

    First picture, the foam could have been placed there by the P.O. to force more air to to the other vents to improve the airflow to those vents. That would be my first guess.

    Second picture looks just like a normal setup except the Factory A/C cars use a formed hard plastic tube rather than the flexible tube you have.

    Third picture, it would not surprise me if that flexible duct is supposed to hook up to the tube there just above the floor. I might be wrong as I don't have a NON A/C unit to look at, but that would be my guess. That might be floor heater tube, but that is much bigger and different than the Factory A/C heater vents at the floor.

    Fourth picture, the drain definitely should not be inside the car. There will be condensation coming off the Evaporator core when the A/C if operating properly, therefore that water has to drain somewhere. I would bet there is either a hole in the floor or firewall that the hose in question fits into.

    My guess at this point is the previous owner got in there to fix the A/C, got confused/frustrated and gave up. Leaving parts disconnected and/or not connected properly. At this point, if it were mine, I would pull the dash at least far enough out of the way to get to the unit behind the dash to verify what is and what isn't connected, blocked off, broken, etc. Otherwise I think you may be chasing your own tail here with the whole situation. Good Luck!

    Haha sorry about the photos.

    the tube, it could be the floor heat, I didn’t try switching it to heat I’ll try that.

    That drain tube actually I traced it to the firewall and it went no where... it was just loose not connected. A second tube was occupying that firewall hole which I followed up to the passenger dash. Now it is one drain tube in new photo

    side note i also noticed my radiator randomly is now leaking but I’ve had it in the Garage without moving lol so ok. Guessing I’ll need a new one



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  15. #40

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    Got my buck tag decoded. No factory AC

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  16. #41

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    Did a little more investigating

    picture number 3 i posted above- that ribbed tube i traced it back to the driver side door dash vent. I further saw that the shape of that tip of the tube matched a plastic openeing at the top of the dash behind the HVAC controls. See photo. This opening must be the top of the blend door apparatus.

    When I inspected the blend door while the vehicle and air was on / running - on the floor setting the air blows out of the floor tubes as expected. I actually found that when I switch to vent, it does not blow harder out of the floor tubes as I thought, but out of a large vent openeing on the blend door apparatus behind the radio - see photo. I put my hand into that and moved the blend doors by hand from the floor which moved the lever on the dashboard so it is all connected but I’m not sure why the vent setting is being directed out of the opening in the photo and not up to the vents

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  17. #42

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    Quote Originally Posted by dynodon64 View Post
    Here are some pictures of a Dealer installed unit out of the car. The smaller unit is the A/C. The larger unit is the stock heater assembly.No heater core in it.
    The heater unit attaches to the firewall as factory installed, and the A/C unit sits above and the heater unit and behind the dash. There is one flex hose missing that goes on the right side of the A/C unit and attaches to the right vent on the passenger side of the dash. The small square hole in the A/C box goes to the passenger side of the dash by the HVAC controls.
    The two hoses tied together go through the firewall for the drain.
    The last two pictures are of the back side of the HVAC control.

    When does the blower motor turn on? When I lever down to the AC selection the compressor doesn’t kick on, I assume due to low refrigerant. But should this blower motor come on regardless? If so, is it connected to a relay to test?
    Last edited by Caseindaplace; 03-17-2019 at 10:03 PM.

  18. #43
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Size:  88.2 KBSo, it’s kind of hard to tell with limited book info. If you look at the ac Module, it has its own blower and blower resistor. I see 3 terminals on the red blower resistor module. That means 2 fan speeds.

    The hvac Module you pictured only shows 1 switch which is activated in the down position. This should somehow engage the ac system. Yes the blower should run without Freon.

    Looking at the parts book, shows one version with additional ac controls in the vent left of the hvac panel which would probably have a fan speed control. Do you have such thing on your car? I have the parts book pictures in my album but could not move them over on my iPad.
    Last edited by KevinK; 03-18-2019 at 12:51 AM.
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    88 Mclaren Mustang Vert 20K miles, 89 Mustang LX Sport Vert,
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    14 Mustang CS/GT, 15 F150 FTX Tuscany, 16 F250 Crewcab, 67 Tbird 47K miles

  19. #44

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    Ah, no I do not have additional Controls on my left vent. The only control I have for the AC is the down position lever for “AC”, On the HVAC control panel. I do have the fan speed selector (3 speeds) on the bottom right of the control panel, but that currently controls another fan that controls the air for defrost and floor. Maybe that same speed controller will control the AC fan once it kicks on? I will check the fuse under the steering column then the relay which i assume just trace the wires from the motor? Good start?
    Last edited by Caseindaplace; 03-18-2019 at 04:57 AM.

  20. #45

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    Quote Originally Posted by KevinK View Post
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Size:  88.2 KBSo, it’s kind of hard to tell with limited book info. If you look at the ac Module, it has its own blower and blower resistor. I see 3 terminals on the red blower resistor module. That means 2 fan speeds.

    The hvac Module you pictured only shows 1 switch which is activated in the down position. This should somehow engage the ac system. Yes the blower should run without Freon.

    Looking at the parts book, shows one version with additional ac controls in the vent left of the hvac panel which would probably have a fan speed control. Do you have such thing on your car? I have the parts book pictures in my album but could not move them over on my iPad.
    Update:

    when I have the air position on anything but Ac the blower in the center dash works 3 speeds. When i push Down to AC, it automatically cuts off that running blower and i would assume transfer to the vent blower on passenger side unless the low pressure switch is denying it to run.

    I tested all fuses and connectors going to the blower motor. Everything has juice. WHen I had the connector unplugged From non running the blower, the working blower was out until i reconnected the connector.

    If you say the dash board blower should run no matter what then I assume the motor is bad. Is there a way to access the motel without taking he whole dashboard apart?

  21. #46
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    Both blower motors operate thru blower resistors for the various speeds. The resistors are those red/orange plates. The blower switched power goes thru them for speeds. Check for power there at the resistors both in and out.

    The pictures posted by the other guy shows 6 terminals on the heater blower. The regular cars have 3 terminals. I wonder if both blowers go through the 1 switch
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    03 Mach 1 7900 miles, 74 Mustang II, 69 Mustang, 67 Mustang, 07 GT500,
    14 Mustang CS/GT, 15 F150 FTX Tuscany, 16 F250 Crewcab, 67 Tbird 47K miles

  22. #47

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    Quote Originally Posted by KevinK View Post
    Both blower motors operate thru blower resistors for the various speeds. The resistors are those red/orange plates. The blower switched power goes thru them for speeds. Check for power there at the resistors both in and out.

    The pictures posted by the other guy shows 6 terminals on the heater blower. The regular cars have 3 terminals. I wonder if both blowers go through the 1 switch
    This is the cable I tested. The multimeter shows voltage. Is this the correct motor for the AC? This motor is all the way against the firewall, same general area as the blower that is behind the passenger side right vent.



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  23. #48

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    I pulled the resistor that the blower motor is hooked up to.

    might have found the issue



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