Charging Original A/C System?

Heating, Cooling & AC

  1. dodge68charger

    dodge68charger Well-Known Member

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    How Are You Guys Going about Charging Your A/C Systems?
     
  2. Cranky

    Cranky Moderator Staff Member FBBO Gold Member

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    Are you talking about using R12?
     
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    • dodge68charger

      dodge68charger Well-Known Member

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      Yes
       
    • Cranky

      Cranky Moderator Staff Member FBBO Gold Member

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      I've seen some 12 on Ebay before but think that's about dried up. Some were converting to 134 with ok results and I did an 88 Dodge Shadow using what was called Freeze 12. I think that was a propane based stuff. Then there's some stuff called Red Tek which is supposed to be compatible with 'all' refrigerants but I have no experience with it.
       
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      • RJRENTON

        RJRENTON FBBO Gold Member FBBO Gold Member

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        IF you can find and afford R12, great....its very effective, and easy to install, providing you have evacuated the system to at least 28" vacuum to remove all traces of moisture, which usually takes about one hour. If you have a sight glass in your system, charge to a clear glass on the suction side if the compressor. A good low side system pressure is approximately 35 psi which should result in approximately 40° F air temp. I'm sure others will have their own opinions and preferences. R134A has similar pressures but the system will be "full" at about 2/3 the volume of R12. Just my opinion of course.
        BOB RENTON
         
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        • 493 Mike

          493 Mike FBBO Gold Member FBBO Gold Member

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          If you convert to 134A the oil should be changed, the service ports need to be changed (adapters are available), and 80% of original R12 charge will be enough 134A refrigerant for a charge.
          I flushed all my system components and even went through the compressor ( for inspection and complete oil change out). I also pulled out the EPR valve on recommendations I found on line. Without the EPR valve there is no control over evaporator temperature so I found a thermostatic, adjustable switch to cycle the compressor to avoid freeze up.
          All my changes are untested as of this date. I won't be able to confirm these changes until warm weather returns.
          Mike
           
          Last edited: Nov 6, 2019
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          • dodge68charger

            dodge68charger Well-Known Member

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            Thanks Guys. That R12 is Hard To Find!
             
          • rebel513r

            rebel513r Well-Known Member

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            I looked on ebay seems there is no shortage there
             
          • dodge68charger

            dodge68charger Well-Known Member

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            Thank You. I ll Check It Out
             
          • bm02tj

            bm02tj Well-Known Member

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            Find a couple of old fridges they used R12 as well
            just make sure they work before you evac
             
          • azmoparboy

            azmoparboy Member

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            Hi, Within the last month I have attempted to rebuild my RV2 compressor twice. The first time it blew oil from side to side on the car. The second one is leaking the same fashion off of the crank but is not leaking as bad. I had rebuilt the entire system to stock and have put in enough money to have actually done it with R134 coolant and a Sanden style compressor. We all know that the R12 is just not good for our fragile world. If it had worked and held the R12 that would have been great, but two times tempted and I’ll not go there again. If you try to use R12 I wish you luck, but remember Mother Earth will thank you if you just use your money on a new upgraded system, I know I wish I had
             
          • Dennis H

            Dennis H FBBO Gold Member FBBO Gold Member

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            R12. Find it. Use it.
             
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            • Demonic

              Demonic Well-Known Member

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              The commercial HVAC industry uses nitrogen to pressure test systems after repairs. Find a friend in the business, and put about 100 psi nitrogen on the system. You'll find your leaks. If you can remove the pulley first, so much the better. That way you can see the shaft seal. It's one of the spots most likely to leak. Be careful with the threads on the condenser outlet, they're aluminum. Use a little light oil on them and the others when assembling.
               
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              • RJRENTON

                RJRENTON FBBO Gold Member FBBO Gold Member

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                Excellent advice. The nitrogen will not introduce any moisture in the system but allow you find the leak. The compressor shaft seal is usually a single unbalanced carbon (the rotating half of the seal assembly) vs ceramic (the stationary half of the seal assembly) of the mechanical seal assembly. The seal is secured to the compressor with O-rings on the shaft and seal housing. It is very delicate and if removing it to replace the O-rings, use caution and do not force or pry or risk damage. Light refrigerant oil, compatible with what ever refrigerant you intend to use on the fittings is also a great idea also.
                BOB RENTON
                 
              • SureGrip

                SureGrip FBBO Gold Member FBBO Gold Member

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                I believe, the rubber hoses also need to be converted over as the molecules in 134A are smaller and will seep out of the older style lines.
                 
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                • 493 Mike

                  493 Mike FBBO Gold Member FBBO Gold Member

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                  Some people converting claim the natural operation of the system (original) seals the pores in the hoses thereby stopping leaks with the new refrigerant. I'm going to try it.
                  Mike
                   
                • bm02tj

                  bm02tj Well-Known Member

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                  I thought it was the oil used with the R134 it did not like
                   
                • YY1

                  YY1 Well-Known Member

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                  my 73 was converted to 134 before I got it using adapter fittings

                  It retains it's original hoses

                  I have had to charge it 3 times since 2012 using a $29 can with gauge

                  blows about 47 degrees
                   
                  Last edited: Nov 12, 2019
                • Demonic

                  Demonic Well-Known Member

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                  Oh boy. True to an extent. The facts are this:
                  Oil and refrigerant have an affinity for each other, they are miscible. As long as the system is in the normal design range, there's no issues. Then it gets complex as time goes by...
                  The R-12 systems used mineral oil. Same base stock as a lot of other things. R-134a uses Polyelkylene Glycol (PAG) oil as installed by the major manufacturers, as 134a has less chlorine than R-12. The two oils are usually not compatible. In the mid 90's, as R-12 prices rose, there was a bit of mixing when there were many cars on the road in both flavors. Eventually, manufactures found that Ester Oil was a better retrofit in 12 to 134a conversions.

                  Bored yet?

                  Now, R-134a still has a higher GWP (global warming potential) than "the latest accepted blend", which is 1234yf. That stands for "Why the f#&! are we changing refrigerants again?" Black hat/conspiracy theory guys say it is because the patent ran out and other nonsense. Whatever. GM, Chrysler and Ford are using it, have been for a few years now. Can't fight the tide.

                  You can buy Ester oil at Advance Auto, Autozone, etc. They also sell PAG oil for the OEM systems. More reading: https://fjcinc.com/understanding-the-differences-between-a-c-compressor-oils/

                  Demonic (25yr commercial/industrial HVAC tech)
                   
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