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Thread: A/C Restoration - R12 vs R134A, etc

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  1. #1
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    Default A/C Restoration - R12 vs R134A, etc

    Let me preface this - I know nothing about A/C! Also, I apologize if there's already a post about this, but I can't figure out how to use the search function on this site for the life of me.

    My 87 V8 Cougar's AC doesn't work - started out as a slow leak and then turned into an issue where it wouldn't keep a charge more than a few months. It got to be a pain, and I just haven't had A/C for a few years now. I would like to get it back up and running, and I'm planning on doing a total system replacement so I don't have to worry about it again in awhile. I've run into a couple questions I was hoping someone could help me with;

    I've found that you can fairly inexpensively replace all the parts of our cars' A/C with Rock Auto parts, which is where I'm currently leaning. However, I've been told that our cars are "R12", which is now hard to get with the newer systems using R134A. If I use these parts, is my system still an R12 system? Is there a way to convert the system?

    I found that LMR.com has a total replacement system designed for a mustang V8 that also claims to convert it to the R134A coolant. However, I've noticed that this system's coolant return line from the compressor to the condenser runs over the engine, past the distributor cap - while mine runs to the right of the engine and then down under it. The compressor also seems to be at a different angle on the mustangs. Has anyone tried to use one of these systems in our cars, and is it worth it?

    Thanks - hope I don't sound like too much of a noob!

  2. #2
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    All things being equal, if your current system was okay, you technically could switch over to R-134 with the system fully evacuated and the old oil sucked out. But if you’re replacing things anyway, you can still convert that to the newer system with an R-134 retrofit kit. Not terribly difficult...just have to be sure the new compressor is okay with either refrigerant.

    For the a/c line you’re referring to, you could use the Mustang upper line, it should fit well. Our cars had a 93” belt with a/c, the Mustang was 91.5”, and that was due to the angle of the a/c bracket as you’ve noticed. I don’t know why our cars got the different line. I used the Mustang line on my Cougar with no problem. However...if you want to be technically correct then you can get a new Cougar line just for that part, and still run R-134 with zero issues.

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    Thanks, Eric - good info!

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    R-12 will work a little better on hot days in stop-and-go traffic. However, you can't buy (unless you find NOS) liquid lines with R-12 sized orifice tubes. I'd go with R-134a. I'd replace the crappy tube/fin condenser that it came with to something better (piccolo or parallel flow). The LMR kits come with them.

    Blow the old oil out of the evaporator. Old oil displaces volume and decreases system performance.

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    Thanks, Jeremy. I found the evaporator on Rockauto, but it's not included in the LMR kit. I can't see this in the engine compartment - I'm assuming it's behind the firewall, on the other side of the accumulator? If so, I'm guessing it's not easily accessible, which is probably why you're recommending to "blow it out" vs. replace it?

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    Unless it's leaking or your compressor grenaded, there's no need to ever replace your evaporator.

    It's a pain to replace.

    I use compressed air and chlorinated brake parts cleaner to blow out the evaporator. Don't use mineral spirits, as it leaves a residue behind.
    Last edited by JeremyB; 04-16-2018 at 11:26 PM.

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    SN-95 condensers fit and are optimized for R-134a. Replace all the black o-rings with green ones. Replace the orifice tube with the same color, but when it's on the machine and charged (15% less R-134a than the labeled R-12 capacity), you'll want to adjust the clutch cycling switch on the accumulator until it engages the clutch until 28 or 30 psi on the low side gauge (blue) before it releases. There is a screw down in the connector on the switch to do this with, I like 1/4 turn increments.
    1988 Thunderbird 5.0
    GT40P, TFS-1, KB domes, 30#, MAF conversion, Explorer GT40 Upper/Lower, Smog delete, Wide Ratio AOD Mod, Unlocked Speedo, 3G Charging System Upgrade, Hi-Torque Mini Starter, 3.73 LSD, BBK 1 5/8 unequal headers, H-Pipe.

    88 Thunderbird/Cougar EVTM
    (Thanks to Trinom for hosting)

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    Quote Originally Posted by TheFoeYouKnow View Post
    SN-95 condensers fit and are optimized for R-134a. Replace all the black o-rings with green ones. Replace the orifice tube with the same color, but when it's on the machine and charged (15% less R-134a than the labeled R-12 capacity), you'll want to adjust the clutch cycling switch on the accumulator until it engages the clutch until 28 or 30 psi on the low side gauge (blue) before it releases. There is a screw down in the connector on the switch to do this with, I like 1/4 turn increments.
    Putting in an SN95 condenser requires cutting of the radiator support and custom mounting brackets. Just use the improved condensers and stick with the stock brackets. Not worth the trouble in my opinion.

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    Quote Originally Posted by TheFoeYouKnow View Post
    SN-95 condensers fit and are optimized for R-134a. Replace all the black o-rings with green ones. Replace the orifice tube with the same color, but when it's on the machine and charged (15% less R-134a than the labeled R-12 capacity), you'll want to adjust the clutch cycling switch on the accumulator until it engages the clutch until 28 or 30 psi on the low side gauge (blue) before it releases. There is a screw down in the connector on the switch to do this with, I like 1/4 turn increments.
    This seems spot on. I have a 88 Cougar 5.0 All stock 88 stuff, new cycling switch and adjusted, Vacuumed down and refilled. Changed nothing else, no leaks, not recharged in 6 years. AC blows very cold and keeps very cool. Mine is a black car in KS summers. If I had to do it again, I would do just what He said above. Fortunately mine worked great stock, just as was.
    Mike

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    Mine fit like OE, and it's from 95.
    1988 Thunderbird 5.0
    GT40P, TFS-1, KB domes, 30#, MAF conversion, Explorer GT40 Upper/Lower, Smog delete, Wide Ratio AOD Mod, Unlocked Speedo, 3G Charging System Upgrade, Hi-Torque Mini Starter, 3.73 LSD, BBK 1 5/8 unequal headers, H-Pipe.

    88 Thunderbird/Cougar EVTM
    (Thanks to Trinom for hosting)

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