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Thread: A/C questions

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    FEP Senior Member Sask84gt's Avatar
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    Default A/C questions

    Trying to decide if I'm going to be running a/c in my 84 gt. One of the previous owners cut the fittings off the accumulator so I would need one of those along with the hoses etc. Question is now that I put a 5.0 HO from a 91 do I buy all the stuff for the 91 motor or for the 84 car. I would be using the compressor from the 91 as its newer. Could someone tell me what I will all need other than accumulator and compressor and for what year I need to buy it. Thanks all!
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    Moderator wraithracing's Avatar
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    I would just buy the A/C stuff as 1984 model. The engine doesn't really matter. Essentially all of the brackets, etc. are the same for the 84-93 cars. The A/C compressor will bolt into the 84 brackets or the 91 brackets without issue. The Accumulator to Compressor hose is different between the 4bbl cars and the EFI cars so keep that in mind. Not sure which you are running. The later Aero Evaporator core changed from a spring lock fitting to a threaded fitting at some point, but I don't recall the exact model/date. That only affects the condenser to Evaporator hose, but keep that in mind if mixing and matching parts. Easiest thing to do is buy for the year model of the vehicle. Easier to keep straight.

    Generally I would recommend the new accumulator, All 3 hoses since they are inexpensive and decay over time. The old hoses don't do well with R134a either. The FS-6 compressor is a good unit and often don't need to be replaced unless leaking or locked up. Clutches often wear out or burn up, but the compressor may still be good. Condenser is a good unit too as long as it is leak free. Obviously you can buy all new if the budget allows or you just want new. Just depends on the condition of your current parts. Same goes for the Evaporator core, if solid and not leaking then should be fine. Just make sure you match your oil to your refrigerant. Good Luck!
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    "I Don't build it hoping for your approval! I built it because it meets mine!"

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    FEP Senior Member Sask84gt's Avatar
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    Thanks Trey! I'm going carb so I will need a accumulator to compressor hose. Also I noticed that the A/C compressor harness is different at least I think it is, cant find any similar connector on my car. What should i do there? The one on my 91 compressor looks like this.
    https://lmr.com/item/LRS-8793SCH/Mus...-Harness-87-93
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    The newer compressor hose is designed to fit around the distributor better and allowing the rubber boot to fit over the cap. I have not laid them out side by side. Personally, if you are using the serpetine belt then I would go with the 91 components. I think everything else is the same except compressor and hoses. I have worked on both my 85 and 89 ac. I could be missing something.

    Update: I assumed the 91 EFI intake and engine controls would be used. The compressor wiring should be simple. Basically 1 wire coming from inside to the low pressure cut out switch and then to the compressor. I’m pretty sure the EFI has a WOT cut out option. I assume it is coming from the computer.
    Last edited by KevinK; 11-11-2019 at 02:24 PM.
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    Moderator wraithracing's Avatar
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    The 86-93 Accumulator to compressor hose routes around the back side of the EFI intake along the firewall. The earlier hose runs down the passenger side of the engine bay and comes across next to the radiator hose in order to clear the air cleaner. The EFI hose routing will often interfere with the air cleaner assembly and especially when using the OEM dual snorkel setup.

    All 79-93 Mustang V8 used the serpentine belt setup. There were changes to the A/C compressors, tensioner, PS bracket, etc. over the years, but all of them were serpentine belt setups. The 85-93 serpentine setup is the same. The FS6 compressor was installed on the factory installed A/C in 1982 and remained the same thru the 93 model.
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
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    1982 GT Stalled RestoModification
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    1986 GT Under going Wide Body Conversion Currently

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    FEP Senior Member Sask84gt's Avatar
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    Ok, I will be using the compressor from the 91 but like I talked about in a previous post the A/C compressor harness seems different.
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    Different as in the connector shape is different? All you need is 12V going to the clutch. Even if the connectors are different between the 84 and 91, the same thing is happening inside either connector. RockAuto sells the electrical connector for the clutch and lists the same part number for 82-93.
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    FEP Senior Member Sask84gt's Avatar
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    Quote Originally Posted by KevinVarnes View Post
    Different as in the connector shape is different? All you need is 12V going to the clutch. Even if the connectors are different between the 84 and 91, the same thing is happening inside either connector. RockAuto sells the electrical connector for the clutch and lists the same part number for 82-93.
    No I mean this harness. Lmr says it's for 87-93. Is this not supposed to connect to my wiring harness? Sorry dont know a lot about this stuff.
    Attachment 130226
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  9. #9
    Moderator wraithracing's Avatar
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    The compressor is the same as I mentioned above. If the engine you have includes the compressor and it appears to be in good shape, then by all means give it a shot.

    The actual pigtail for the compressor is the same. The engine wiring harness is completely different from a 1991 to a 1984. Actually the 84 is different than the 85, which is different from the 86, which is different from the 87 and . . . . You get the idea.

    Is your plan to install the 91 engine with the EFI or are you running a carburetor? That will determine which harness is correct for your setup. You can swap in the 91 EFI setup and harness, but you will have to do some custom wiring to make everything work properly. The more information you provide in regards to your setup the better information we can provide.
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
    1986 GT Under going Wide Body Conversion Currently

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  10. #10
    FEP Senior Member Sask84gt's Avatar
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    Quote Originally Posted by wraithracing View Post
    The compressor is the same as I mentioned above. If the engine you have includes the compressor and it appears to be in good shape, then by all means give it a shot.

    The actual pigtail for the compressor is the same. The engine wiring harness is completely different from a 1991 to a 1984. Actually the 84 is different than the 85, which is different from the 86, which is different from the 87 and . . . . You get the idea.

    Is your plan to install the 91 engine with the EFI or are you running a carburetor? That will determine which harness is correct for your setup. You can swap in the 91 EFI setup and harness, but you will have to do some custom wiring to make everything work properly. The more information you provide in regards to your setup the better information we can provide.
    I already stated in a previous post that i was going carb. I switched the 91 motor from efi to carb to fit my original carbed 84. I just looked to see if there was a connector on my 84 harness that matches the end on the harness for the compressor and camt seem to see one.
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    85 Gt

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    The ac harness on my 85 includes the oil pressure and coolant sensor. It also has the low oil level. It’s not too long and must terminate near the front of the drivers strut tower. I have mine out right now and only disassembled that area. Two square gray connectors.

    Did not see the mention of using the carb. I would use the 84 parts to keep it simple for now and later.
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  12. #12
    Moderator wraithracing's Avatar
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    Quote Originally Posted by Sask84gt View Post
    I already stated in a previous post that i was going carb. I switched the 91 motor from efi to carb to fit my original carbed 84. I just looked to see if there was a connector on my 84 harness that matches the end on the harness for the compressor and camt seem to see one.
    Sorry I missed that in the previous post. Unfortunately with the constant reference to the 91 engine and then the wiring harness it made me think you were staying with the EFI.

    As stated above the A/C clutch pigtail should be on your engine harness that will connect to the engine bay harness via 3 large pigtails IIRC. If yours is missing or in bad shape this is an option, although not an inexpensive one. Good Luck!

    https://www.foxresto.com/1984-Mustan...-p/4784001.htm
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
    1986 GT Under going Wide Body Conversion Currently

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

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    FEP Senior Member Sask84gt's Avatar
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    First off thanks to you both for being patient and helping a newbie out with this stuff. I knew as soon as I got to the wiring I'd be needing some big time help. Ok so this is what I have.
    Attachment 130232
    I Dont see anywhere on this to connect this end from the compressor harness.
    Attachment 130233
    I do have the clutch cycling switch and the harness.
    Attachment 130234
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    84.5 Gt T-top
    85 Gt

  14. #14
    Moderator wraithracing's Avatar
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    The 84 harness you have will not connect to the pigtail off of the 91 Compressor. The wiring harness is completely different between the 91 and the 84.

    Looking at your harness laying on the ground, it appears the A/C clutch pigtail is the long wire on the bottom right hand side of the picture. Black wire with yellow hash stripes. If I am correct that should plug into the clutch directly when you remove the current pigtail off of the compressor.
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
    1986 GT Under going Wide Body Conversion Currently

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

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    I am currently repairing a similar harness on my 85 cfi. Oil pressure, coolant temp, oil level and ac compressor are the only items on it. The carb one looks like a few more wire. Yes, black with yellow hash marks is ac compressor. The connector should be available.
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    14 Mustang CS/GT, 15 F150 FTX Tuscany, 16 F250 Crewcab, 67 Tbird 47K miles

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    FEP Senior Member Sask84gt's Avatar
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    Thanks guys, you were right,the black with yellow hash Mark's fit into the compressor. Not knowing what any of the wires are makes it tough to know where they go lol. In my pic of my harness is the silver pipe with the brackets and the 2 cut off hoses the a/c condenser that attaches to the rad?
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    85 Gt

  17. #17
    Moderator wraithracing's Avatar
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    Quote Originally Posted by Sask84gt View Post
    Thanks guys, you were right,the black with yellow hash Mark's fit into the compressor. Not knowing what any of the wires are makes it tough to know where they go lol. In my pic of my harness is the silver pipe with the brackets and the 2 cut off hoses the a/c condenser that attaches to the rad?
    I am not sure what the silver pipe with brackets is. It almost appears to be a brake line or something, but I would need a better closer pictures to be sure. Doesn't appear to be an A/C line to me.

    You accumulator with the one end cut off, attaches to the Evaporator core at the firewall. The existing fitting will thread onto the Evap core and the missing line on the other side will go to the driver side fitting on the Compressor. The Passenger side fitting on the compressor will have a hose that goes to the top line on the condenser and then there is the liquid line/office tube line that will go from the bottom fitting on the condenser to the remaining fitting on the Evap Core. The A/C condenser is a radiator looking piece that sits in front of the actual engine radiator and has two spring lock fittings that come out on the passenger side of the radiator just to the outside of the upper hose fitting on the radiator.

    A/C Condenser

    Name:  AC Condenser.jpg
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    Accumulator or Receiver Dryer with hose You have to make sure you get the correct one. Most now list the 86-93 EFI Accumulator as correct for the earlier cars which is not! The two fittings on the accumulator need to face 180 degrees from one another, otherwise it is not correct for a carburetor setup.

    Name:  Accumulator.jpg
Views: 129
Size:  22.4 KB

    Condenser Hose to Accumulator hose, Liquid Line/Orifice Line

    Name:  Liquid line.jpg
Views: 129
Size:  16.9 KB

    Compressor to Condenser hose or Discharge Line

    Name:  Discharge Line.jpg
Views: 129
Size:  26.9 KB

    Hope that helps!
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
    1986 GT Under going Wide Body Conversion Currently

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  18. #18
    FEP Senior Member Sask84gt's Avatar
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    Thanks Trey that helps a lot! I took a couple more pics of that silver pipe with brackets for ya. Not sure why this site always turns them sideways lol
    Attachment 130290
    Attachment 130291
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  19. #19
    Moderator wraithracing's Avatar
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    The line appears to be emissions related. Unfortunately I have am not really familiar with much of the emissions stuff. Most of my Foxes are engine less when I buy them or have already been modified and therefore no emissions related stuff. Hopefully another member can help out with that.
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
    1986 GT Under going Wide Body Conversion Currently

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  20. #20

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    Not 100% but those valves look like the fuel bowl vent solenoid on my sons 1980 vintage except there are two of them (probably for two bowls ?l).

    I believe they open up to vent the fuel vapors to the charcoal canister when the car is shut off.

  21. #21
    FEP Senior Member Sask84gt's Avatar
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    Quote Originally Posted by at_the_junkyard View Post
    Not 100% but those valves look like the fuel bowl vent solenoid on my sons 1980 vintage except there are two of them (probably for two bowls ?l).

    I believe they open up to vent the fuel vapors to the charcoal canister when the car is shut off.
    Ok, so I guess my next question for anybody that knows. Can i get rid of it or is it something that's needed? I was planning on getting rid of charcoal canister.
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    That may depend on the emission regulations where you live. The car will run fine without most of the emission stuff.

  23. #23
    FEP Senior Member Sask84gt's Avatar
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    Quote Originally Posted by darkd0r View Post
    That may depend on the emission regulations where you live. The car will run fine without most of the emission stuff.
    No emission regulation crap where I live.
    Mustangs
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    85 Gt

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