A/C question 12 to 134A

Discussion in 'General Discussion' started by cycloneman, Jul 7, 2011.

  1. cycloneman

    cycloneman Well-Known Member

    Dec 16, 2008
    How to swap out 12 to 134a on a vehicle. 86 chevy monte carlo. I have often fixed the old 12 units but never fooled with the 134 ref. I know it req different gages and such. But does the condenser or evaporator need to be replace, compressor ect?
  2. woolleyworm

    woolleyworm Well-Known Member

    Feb 23, 2009
    SW Fort Worth

    Oil, fittings and orfices need to be replaced. I know that they have kits avail, I'll do some checking and see if I can find one for ya.

    I'd just put some R12 in it if you can get ahold of some, but I know that it's getting difficult to find nowadays.

  3. Marlin T

    Marlin T Well-Known Member

    Jul 8, 2005
    New Mexico
    It shouldn't be that hard to switch over.

    Drain system
    Evacuate system
    Add oil if needed

    You shouldn't need new gauges as they are after all only gauges.

    Think of it as switching from 10W-30 to 20-50. They both do the same thing.

    But the trick is in having the right equipment.
  4. cycloneman

    cycloneman Well-Known Member

    Dec 16, 2008
    Right gages are gages but they connect with different size connectors and 134 i believe has a quick style connector.

    But anyway lets get back to the system. How would you drain the oil from the system? I imagine you take the compressor off and manually drain? What about the lines? Blow them out then flush with 134, make your seals, suck down to a vaccume and recharge?
  5. Slabsides

    Slabsides Member

    Jul 22, 2009
    L.A. (Lower Alabama)
    Try to find some "Freeze 12". The stuff works great in R12 systems and it's legal/safe.

    I have never seen an R12 system converted to R134 that worked worth a darn. R134 is not as efficient as R12, so 134 systems run at higher pressures and have larger, more robust components to get the same result. This is why, when you convert one, they never cool as good and they tend to fail from the extra stress. Most converted systems will cool decent at highway speeds, but are not powerful enough at idle. (adding electric fans at the condensor helps, but it's never as cold as before with R12)

    I have noticed bad luck with GM, Hondas and Subarus. Even after being flushed, correct oil added and serviced, I have seen compressors lock up. Some people have had decent results, I'm sure, but I have not personally seen any.
    Last edited: Jul 7, 2011
  6. Marlin T

    Marlin T Well-Known Member

    Jul 8, 2005
    New Mexico
    If your system isn't leaking you most likely don't need to add oil. If you find the leak and the connection is oily you can add the oil after you evacuate the system, right before you add the new 'freon'.

    You will not have to take the compressor off either way.

    JUNKKING Well-Known Member

    I had a vehicle converted an 86 olds cutlas and it worked fine but it wasn't cheap even having my friend who is a GM master mechanic do the work. There are alot of parts that need to be changed to make it run efficient. I know r134a last year was 5 bucks a can anywhere you looked this year near 15 dollars a can and was told its going up near 25 a can before the end of the year. Check out this site out to see what really needs to be done. http://www.gnttype.org/techarea/airconditioning/R12toR134a.html
  8. Big ugly

    Big ugly New Member

    Feb 27, 2009
    Knoxville Tennessee
    You have to have the system evac'ed if not it will blow the seals in the condensor. I just went trough this earlier this year on my Buick
  9. I had help converting a '93 Buick LaSabre from R12 to 134a. We had to replace the compressor because it had 'locked' up a few days before and since the compressor had to be changed, we put 134a in it. Of course, the new compressor is not warranted if you don't replace the drier unit at the same time. So we replaced the compressor, drier, and all of the O-ring seals. I ran the car for about 5 or 6 years with no problems. Then some company (I don't remember who) started selling a 'kit'. I bought one at Walmart for $34.95 and another one later. The instructions said to drain the system, close the system and add the 134a with an oil that was compatible with the old oil in the system already mixed with the freon. I had an '89 Jeep Cheroke that was low on freon when I bought it used. It was so low that I opened the system and got not even a 'hiss'. I replaced most of the O-rings and didn't even purge the system or evacuate it (suction it down). After I added the freon, I used the Jeep for about 2 years before selling it. I had no trouble with it and it cooled really well; even idling. I also did the same thing to a '78 Fairmont, but two weeks later one of the hoses burst. They were old and of course the 134a is higher pressure. I did not have gauges on the Jeep or Fairmont. My friend that helped me with the Buick had gauges and a vacuum system. I can't tell you what to do; but that is the experience I have had with the conversions to 134a. Good luck with what ever route you take!
  10. cycloneman

    cycloneman Well-Known Member

    Dec 16, 2008
    Learning enough about this to be a pro.

    1. I cant be sure if the compressor is leaking from the front seal. I know it was leaking from the rear seal where the hoses mount up to it. So i am going to replace the compressor. I have ordered one and it should be in tomorrow. I originally took off the compressor to drain the old oil. But after I got it off I could not say for sure if the front seal was not leaking. I saw alot of residue all over the thing so its better to be sure.

    2. I flushed the system today. I had oil in the high side line to the condensor. I also had a good bit of oil in the condenser. I flushed the evap too. It takes some time for the flush to evaporate even after you blow air in the system to remove it. But to me this is a necessary step.

    3. I replaced all the o rings with new green ones.

    4. I am going to replace the accumulator (sp). I heard that the accumulator will always hold oil so it is a good idea to change it. I agree. I took the old one out and cut it open to see what was inside. There is basically a tube that makes a u turn in it with a small hole at the bottom. There is a screen around this hole i guess as a filter. Then there is a bag of sorts that goes around the tube. This bag is filled with tiny pellets that absorb oil. The bag also acts as a filter. To me this is a must change item, especially if you are going to change freeon types.

    5. I plan to put everything back together and leave the high side line to the accumulator off. I then plan to run a little bit of 134 in the system then seal it up. At that point i will suction it down. From there its just a matter of charging it.

    If anyone ever needs to know how to do this just ask me.
  11. Double D

    Double D Administrator Staff Member Supporting Member

    Jul 16, 2009
    North Florida
    Do not replace your accumilator and leave the system open. The desicant pouch is designed to take the moisture out of the system and it will suck the moisture out of the air if you leave lines off. There is suppose to be oil in the lines and the condensor. So, once you change your parts, seal it up or you will be changing your accumilator/ drier again.
  12. cycloneman

    cycloneman Well-Known Member

    Dec 16, 2008
    I Know. I have not installed the dryer yet. I still dont have my compressor.

  13. JLA

    JLA Well-Known Member

    Feb 26, 2007
    Heart Of Texas
    Every one I have ever converted usually ends up with busted seals in the compressor. As slabsides noted, R12 systems were far more efficient than R134a and run at much lower pressures, converting to 134 almost doubles working pressure and blows out the seals in the pump eventually.. I find, with R12 systems, once they stop working, its best to either bite the bullet andpay thru the nose to have it professionally converted to run R134, or use the free 2 or 4 X 60 a/c every automobile has built in..;)
  14. cycloneman

    cycloneman Well-Known Member

    Dec 16, 2008
    OK done.

    I changed the compressor too. The old compressor was leaking from the 2 o rings in the back. I decided to change the compressor for the heck of it casue i didn't know if the front seal was leaking. It was dirty so i decided to do it anyway.

    However - When i charged the unit the low side was at 55 psi with just one can of 134a - way too high. So i left it alone for a couple of days. I went back and put gages back on the car. Now the gages showed an even 70 psi on both sides. I turned on the compressor and it did not move refrigerent. The gages stayed the same. SO I took off the new (not rebuilt) compressor only to find bits of metal here and there. Great! So i brought it back, flushed the system again and reused the old compressor with new seals. Charged it up and it works great. Ac is nice.
  15. JLA

    JLA Well-Known Member

    Feb 26, 2007
    Heart Of Texas
    Mine went out on the ranger. Dadgum dryer canister popped a leak in it.
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