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Thread: R12 or R134?

  1. #1
    Junior Member
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    R12 or R134?

    My AC quit working at the end of summer. For a while, the compressor cycled on and off constantly -- 2 seconds on, 2 seconds off -- over and over and didn't cool well. Now, the compressor won't activate at all (it tries for a split second the first time after the car has been sitting, but it immediately cuts out )

    I suspected a leak. When I started poking around, I noticed that the high and low pressure ports are the R134 style. The Sanden compressor appears to be original, and it clearly says "R12" on the label.

    I have some service history from a prior owner -- there was a lot of AC work done around 2003 with some new hoses (can't tell which) and a new condenser. One of the invoices specifically says "Freeze 12" which, if correct, means it was still R12 at that point.

    How do I have R134 ports with an R12 compressor, or is that a normal thing to end up with over the years? And is there any way to know for sure what refrigerant is in there?

    Thanks for your help on my first-ever post!

    delo-compressor2.jpg

  2. #2
    Senior Member r00b's Avatar
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    Quote Originally Posted by fz2 View Post
    My AC quit working at the end of summer. For a while, the compressor cycled on and off constantly -- 2 seconds on, 2 seconds off -- over and over and didn't cool well. Now, the compressor won't activate at all (it tries for a split second the first time after the car has been sitting, but it immediately cuts out )

    I suspected a leak. When I started poking around, I noticed that the high and low pressure ports are the R134 style. The Sanden compressor appears to be original, and it clearly says "R12" on the label.

    I have some service history from a prior owner -- there was a lot of AC work done around 2003 with some new hoses (can't tell which) and a new condenser. One of the invoices specifically says "Freeze 12" which, if correct, means it was still R12 at that point.

    How do I have R134 ports with an R12 compressor, or is that a normal thing to end up with over the years? And is there any way to know for sure what refrigerant is in there?

    Thanks for your help on my first-ever post!

    delo-compressor2.jpg
    A shop can test what gases are in there. I once took my car to have the r12 filled since it had a slow leak and stopped working. They said they needed to test it first because some people put propane in their AC. After the test he said it was 100% r12.

    Also Freeze 12 is a refrigerant that is 80% R134a and 20% R142b, those r134 ports look like adapters that screw on.

  3. #3
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    I agree, it looks like someone screwed -134 adapters onto your -12 service valves. Try to stay with -12, nothing will cool as well as R-12 with the stock A/C system. On a lot of the cars I have worked on, even after replacing a lot of parts, there were still slow leaks. There are good leak sealers now that actually work. Have your shop use a leak sealer and top off with R-12 or Freeze -12. They should also check the oil in the compressor and remove the adapters and fit new valve cores. Use metal (brass) caps on the service valves.
    David Teitelbaum

  4. #4
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    Quote Originally Posted by David T View Post
    , nothing will cool as well as R-12 with the stock A/C system.
    Absolutely not true. There are at least 11 cars here in AZ to prove it.

    A PROPER R-134A conversion will match or beat R-12 in performance and reliability. Also, R-12 is approaching $170/lb, at least in my area.

  5. #5
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    Quote Originally Posted by Ethan Rode View Post
    Absolutely not true. There are at least 11 cars here in AZ to prove it.

    A PROPER R-134A conversion will match or beat R-12 in performance and reliability. Also, R-12 is approaching $170/lb, at least in my area.
    Just what exactly is a "Proper" conversion? What is done besides changing the refrigerant and oil, and putting the adapters on the service valves? In my experience you lose about 10% cooling capacity switching to -134.
    David Teitelbaum

  6. #6
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    Quote Originally Posted by David T View Post
    Just what exactly is a "Proper" conversion? What is done besides changing the refrigerant and oil, and putting the adapters on the service valves? In my experience you lose about 10% cooling capacity switching to -134.
    A proper conversion would be to replace the stock condenser with a parallel flow one, a compressor that is designed for R134a (since R134a operates at a higher head pressure) and upgrade the old aging hoses to modern hoses to prevent leaking past the hose itself and fittings. With R12 at $170lb @ 3lbs needed for the Delorean, the costs of converting (if you source parts yourself and install them) VS recharging R12 in the original system, the costs are a wash.

  7. #7
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    Quote Originally Posted by dmcman73 View Post
    A proper conversion would be to replace the stock condenser with a parallel flow one, a compressor that is designed for R134a (since R134a operates at a higher head pressure) and upgrade the old aging hoses to modern hoses to prevent leaking past the hose itself and fittings. With R12 at $170lb @ 3lbs needed for the Delorean, the costs of converting (if you source parts yourself and install them) VS recharging R12 in the original system, the costs are a wash.
    Do you still use the orifice tube or do you change it to something else like the VOV? As for the compressor, it is basically the same as the R-12 one with a higher pressure relief valve and different oil. For the hoses, no one should be operating with the original hoses anymore, they are too old and they are too leaky. Even if you don't convert to -134, the hoses should be replaced and use the newer barrier type hose that can handle the higher pressures of -134 and leak a LOT less. So the big thing about your "proper" conversion is to upgrade the stock condenser to a higher efficiency, parallel flow type. Last point, what is the Delta T at, say, 100 degrees ambient temp? At 100 degrees what is the outlet temp at the center vents?
    David Teitelbaum

  8. #8
    Senior Member 82DMC12's Avatar
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    I've had both VOV and fixed orifice tubes and honestly I didn't notice a difference either way. I have a white orifice tube in right now but I did buy a couple of the blue ones which I hear might be better for the DeLorean 134a conversion. Can anyone comment on white vs blue orifice size and real world results? I can get low 30's vent temp with my system but it takes a few minutes to cool down on the hottest days. I'm sure tint would be helpful...

    Last year I replaced my Futura barrier hoses (from Hervey so many years ago) with DPI's cut-to-fit A/C hoses which are actually Danfoss EZ Clip hose system. The nice thing about the DPI kit is you get everything you need with no research required, though these parts are not DeLorean specific. They are quite a bit narrower than barrier hoses so it took me 4x as long to cut up and yank the hoses than it did to run the new ones. I can't recommend them enough. I bought extra clips and cages, etc so I can do repairs later if needed. Here's a photo showing the difference in size. Top hose is old barrier, bottom hoses is Danfoss (low side hose).

    PXL_20230318_001428693.jpg
    Andy Lien

    VIN 11596 Jan 1982 build - owned since Nov. 2000!
    Total frame-off restoration completed 2021-2023

    Photography and Backpacking is life.

    Was Fargo, ND
    Now Kansas City

  9. #9
    Senior Member Bitsyncmaster's Avatar
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    It's best to compare vent temps not using re-circulation (max). With max air you can get very cold running a long time in the shade. With outside air it's a more stable test of how well the system can cool (does not matter if in sun or shade). I test with doors open and fan on speed 4 for a static test (normally get 60 F in 90 F air). With car running down the road it will get a lot colder (normally get 40 F in 90 F air).

    But the only real test is, Does your AC keep you cool on the hottest sunny day while driving.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  10. #10
    Senior Member 82DMC12's Avatar
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    Quote Originally Posted by Bitsyncmaster View Post
    It's best to compare vent temps not using re-circulation (max). With max air you can get very cold running a long time in the shade. With outside air it's a more stable test of how well the system can cool (does not matter if in sun or shade). I test with doors open and fan on speed 4 for a static test (normally get 60 F in 90 F air). With car running down the road it will get a lot colder (normally get 40 F in 90 F air).

    But the only real test is, Does your AC keep you cool on the hottest sunny day while driving.
    Right. I think we get spoiled by modern cars with great factory tinting and an engineered A/C system that used 134a or 1234yf from the start. But let's face it, if it's 95F and high humidity, it takes quite a few minutes of driving my new Audi before it feels comfortable. You have to remember the A/C has to cool down the seats, glass, dash, carpet, etc too before it starts to feel "nice" inside. In the DeLorean, if after 15 minutes I'm not sweating and after 20 minutes I can turn the fan speed down to 2, I would say that's pretty damn good.
    Andy Lien

    VIN 11596 Jan 1982 build - owned since Nov. 2000!
    Total frame-off restoration completed 2021-2023

    Photography and Backpacking is life.

    Was Fargo, ND
    Now Kansas City

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