Register now to get rid of these ads!

Hot Rods How hard is it to change over to 134R freon?

Discussion in 'The Hokey Ass Message Board' started by Bruce Fischer, Mar 23, 2019.

  1. I still have the old R12 {I think that's what its called}set up in my station wagon. How hard is it to change over to 134 R? I cant stand the humidity here in the summer and I want a nice cool car to drive back and forth to work this season. HI to you all and Thanks for any input. Bruce.
  2. David Gersic
    Joined: Feb 15, 2015
    Posts: 1,836

    David Gersic
    from DeKalb, IL

    Is it working now? If so, changing to R134a won’t matter. If not, do you want it easy, or cheap?

    Sent from my iPad using The H.A.M.B. mobile app
    Bruce Fischer and porknbeaner like this.
  3. If your system is still holding pressure why change?

    Back in the day... People would dump it add the fittings and go... minus about 15% (if I remember correctly)
    Most of your local auto parts stores has the conversion fittings on the shelf... also depends on the year of the wagon also..
    Bruce Fischer likes this.
  4. Someone smarter than me will chime in I'm sure. But I've never done anything but flush and fill. Still working years later.
    Bruce Fischer likes this.
    Register now to get rid of these ads!

  5. You must change the lube oil to PAG oil. R12 uses mineral oil and they are not compatable.You will need to evac(flush) the system.R12 cools much better if you can keep it.Others will give you more professional info.
    Bruce Fischer and JeffB2 like this.
  6. Oh and I forgot...…. use ESTER oil for the conversion if you flush
    Bruce Fischer likes this.
  7. kevin31
    Joined: Oct 1, 2011
    Posts: 35

    from ottawa

    We do a lot of a/c work at our shop, evacuating and vacuuming the system will not remove anywhere near all of the oil in the system. Truthfully you are better off either finding someone with leftover r12 to recharge the system or using the off the shelf r12 capatible canned recharge kits, when r12 is converted to 134 it doesn’t cool quite as well and the system will slowly leak, 134 molecules are smaller than r12 and refrigerant very slowly leaks through the old rubber hoses and such, do yourself a favor and keep it r12

    Sent from my iPhone using H.A.M.B.
  8. 65pacecar
    Joined: Sep 22, 2010
    Posts: 685

    from KY, AZ

    R12 was outrageous for a while but now you can find cans at a decent price at most swap meets or if you know someone that stick piled it years ago. Still expensive but if you have a good system I would keep using it. I have converted a few cars to 134 with good luck though.

    Sent from my iPhone using The H.A.M.B. mobile app
    Bruce Fischer likes this.
    Joined: Jan 7, 2016
    Posts: 1,298


    I am an old freon jockey from way back, and the statement that 134a doesn't cool as well is correct. If the system isnt leaking. Keep it R12 even if the cost is high if you can find it. If you do the conversion, keep in mind that EVERYTHING must be flushed and it all needs to be cleaned well. If you dont get everything cleaned well and replace the drier, you will have components fail. I did a complete flush on an OT Jeep Cherokee a few years ago. I replaced the compressor , the condenser, and the expansion valve, the drier after flushing everything very well and several of the lines that looked old and cracked. Never had to add any refrigerant but it just didnt cool as well as it did on R12.
  10. metlmunchr
    Joined: Jan 16, 2010
    Posts: 721


    Agree with Kevin 100%. To do a proper conversion to 134 requires a compete flushing of the system to remove all oil as well as replacing all hoses with barrier type hoses that won't let 134 leak thru, as well as replacement of the expansion valve. And, when you're done, you end up with a system that won't cool as well as it would with R12.

    Either way you go, you'll need to chase down and fix any significant leaks in the system. From my own experience in fooling with auto a/c systems over the last 40 years, I'd say 95% or more of leaks occur at either fittings (where hoses are crimped to hard lines, or at connections to the compressor) or at the compressor shaft seal. Because refrigerant carries oil with it continuously thru the system, the most telltale sign of a leak is oil around a connection or, in the case of a shaft seal leak, oil around the clutch and front of the compressor body.

    Don't be tempted to use any of the replacement refrigerants that claim to have a stop leak ingredient. You'll have problems down the road and people who work on automotive a/c won't touch any system with stop leak as it will mess up their serivicing equipment.
    Bruce Fischer, JeffB2 and RMONTY like this.
  11. ricko1966
    Joined: May 4, 2017
    Posts: 35


    When I was still working at dealerships, first protocol by Honda was replace all orings, replace receiver dryer,evac and fill,with 85 percent charger.By the end that had been revised to replace receiver dryer,evac. The system ,refill with 85percent charge.A vacuum pump for your systen is easy to Fab with an old refrigerator compressor.Evac and pulling vacuum is an important step.
    Bruce Fischer likes this.
  12. porknbeaner
    Joined: Sep 12, 2003
    Posts: 40,959


    134A is an R12 replacement. I have dumped old systems and pulled a vacuum on them and just dropped the 134A in. Now for my disclaimer that is the wrong way to do it.

    There is actually a kit you can buy from most autoparts stores for converting. It comes complete with instructions that include your proper head pressure. Pretty basically fool proof. You will still need a Vac pump and access to gauges. If you are not a refrigeration mechanic or have never done it before or both I suggest buying the kit.
    Bruce Fischer likes this.
  13. I had to top up an older, R12 system recently, and was told to use R12a. It has been working fine since last summer. It is a simple procedure, just follow the instructions to the letter.
    If you have the older system with the screw type, Schrader, fittings, there is an adapter that comes with some kits, but can also be bought separately, that allows you to add the R12a to the 134 system.
    Read every line of the manufacturers instructions before buying the product.
    The one I bought was called Red Tek, but it may only be a Canadian brand.
    Bruce Fischer and VANDENPLAS like this.
  14. Ziggster
    Joined: Aug 27, 2018
    Posts: 204


    Spent almost half my career designing mobile HVAC systems. You can switch over from R12 to R134a without switching any hoses, expansion valve, etc. R134a will NOT leak through the hoses as the old mineral oil has created its own barrier on the inside of everything. I would not switch unless I had to, but if you must, as others have pointed out, you need to get rid of the old mineral oil as much as possible. That means a flush, draining the compressor, and getting a new filter drier.
    Bruce Fischer likes this.
  15. okiedokie
    Joined: Jul 5, 2005
    Posts: 3,516

    from Ok

    Been nothing but a hobby hack so I have nothing of value to add. That being said, a few years ago had a relative that needed transportation and my in-laws had an older car they gave her. This was summer in Oklahoma so a/c is desirable. The car had an r12 system that was empty of Freon, well it didn’t cool at all. Having no interest in investing any money in a car that was basically a throw away and she had no money, I decided to try something. I changed the fittings ( adaptors I think, been a few years) added R134 and it cooled great. I had to recharge it the second summer but it still cooled well the second summer.
    egads and Bruce Fischer like this.
  16. Dyce
    Joined: Sep 12, 2006
    Posts: 1,768


    I remember when the manufacturers switched to r134 they went to bigger condensers to compensate, and on orifice systems they changed that to.

    It will work for a few years or more if you screw adapters on and charge it up with r134. You can flush the system all you want but you will never get all of the oil out of the compresor. If it was me I would leave it r12. But if I did change it over I wouldn't go to to much trouble flushing it.

    Now if the compresor is bad, that is different. I would for sure flush it and switch to r134.
    egads and Bruce Fischer like this.
  17. ebfabman
    Joined: Mar 10, 2009
    Posts: 592


    How much smaller can they be? R134a is a 2 carbon molecule and R12 is a single carbon molecule. They're molar masses are similar.
    Bruce Fischer likes this.
  18. Boneyard51
    Joined: Dec 10, 2017
    Posts: 2,064


    Not recommending this, just relaying my experiences. There are thousand different opinions out there.
    Back when R12 went away, I changed my Dads ot pickup like you were “supposed “to, that was flushing, new o rings, new dryer etc. After all that , all it would do was cool moderately, and had to be recharged occasionally.
    A female friend came by and wanted me to put a can of 134A in her car, which was a R12 car. Her car was cooling, just not enough. I told her that was not a good idea. She insisted, I did it. I put one can of 134A in on top of a 1/2 charged R12 system. That car would freeze you out and she drove it several years in the Oklahoma summers, before the car quit. The A/C was still working.
    After that, I just dumped, flush, and recharge with a litte oil. Never had any of the problems everyone said I would. And we work our A/Cs hard here in Oklahoma. Didn’t do a huge number of them during that time, maybe 25 or so , with similar results.
    Just my experiences.

  19. David, just blowing warm air right now. I am going to pull a vaccum on it to see if there are any leaks.1st.Thanks.Bruce.
  20. Thanks guys .I was hopping to keep it R 12 because of it being cooler. I will let you know how it works out .Thanks Bruce.
    Boneyard51 likes this.
  21. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 7,361


    Plus different fittings
    Bruce Fischer likes this.
  22. riv63
    Joined: Feb 2, 2008
    Posts: 79

    from Texas

    you can also use air duster. I have several vehicles using it. Cools great. 3 for $10 at Sam's Club.
    Bruce Fischer likes this.
  23. What Kevin31 and maybe some others' they fazed it out R12 here - we had some likeable stuff called - freeze 12 - ran it in most all my early pre 70's cars after the turn of the century with out issues.
    Bruce Fischer likes this.
  24. BJR
    Joined: Mar 11, 2005
    Posts: 5,533


    I had a friend that had an old 70's Cadillac that was just a driver. The air conditioner didn't work and was found to be low on freon. He topped it up with 134A and ran it for the next 8 years with no problems. Now I know you are not supposed to do this but it worked for him.
    egads and Boneyard51 like this.
  25. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 4,582


    I've used a refrigerant called Freeze 12 which is a replacement for R12. It seemed to work as well as R12.
  26. David Gersic
    Joined: Feb 15, 2015
    Posts: 1,836

    David Gersic
    from DeKalb, IL

    Put a gauge set on it. It’s probably leaking, and discharged.

    Sent from my iPad using The H.A.M.B. mobile app
    Bruce Fischer likes this.
  27. Thanks mgtsumpy, I needed to know that. Bruce.
  28. O.K. Riv63, as most guys on the H.A.M.B. I am just a simple guy. What the heck is air duster??? LOL. Thanks Bruce.
  29. David, that's the plan buddy if its leaking find out where and replace the part .Thanks. Bruce.
    Joined: Dec 14, 2009
    Posts: 1,715


    Hook up a seat of gauges and a vacuum pump.
    I have used the jerry-rigged refrigerator compressors before. They work ok but won’t pull a deep vacuum.
    Try to pull 28” of mercury .... more vacuum the better and once you get to that point hold the vacuum for a minimum of 45 minutes.
    If it holds your safe to just recharge the system.
    If it won’t pull or hold that vacuum you have a big leak that needs fixing.
    Lots of talk what to replace etc. I’ve done nothing but fittings and oil and never had an issue.
    I like replacing the dryer on cars I like and want to keep.
    There are universal oils that blend with r12 and 124 oils.
    I’ve used the little cans of tedtek and bluecool etc on stuff I don’t care about. Never had an issue with that stuff, but if you ever want to fix it properly after using a stop leak or “blended” refrigerant you are going to have issues.
    Good luck
    Boneyard51 likes this.

Share This Page

Register now to get rid of these ads!


Copyright © 1995-2020 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.