R12 -> R134a Conversion - Harder than I thought.

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  1. #1
    Junior Member houckman's Avatar
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    Jun 2003
    Leesburg, VA

    R12 -> R134a Conversion - Harder than I thought.


    I hope I am not posting a duplicate, but I did the searching and could not find exactly what I am looking for.

    My A/C did not work on my 82 L-Type. I knew it had a leak, and was emply of refrigerant and that it was still R12, but that was about all I knew. So I thought I convert it to R134a and use a leak-sealing refrigerant. Realize I know nothing about A/C systems..... or really even cars for that matter.

    So, I bought the conversion package for ~$30. The instructions seemed so simple: "Find high-side service port, put adapter A.... Find low-side service port, put adapter B..... fill 134a refrigerant via low-side service port. Adapter A will not fit low-side and adapter B will not fit high-side." This is paraphrased, but you get the idea..... easy.

    Well, I did not find two ports, I found four.... two on the compressor, one near the dryer and one just kind of running on the line leading to the cabin. All of these are identical fittings... so adapter B fits all of them and adapter A fits none of them. So much for easy. :? I don't know which is high, which is low, etc. Maybe all are low since same fitting, but I doubt it.

    The instructions also seem to indicate that the port running between the compressor and the dryer was high side. Well, I had two of those. While given an adapter for the high side, there were no instructions to actually do anything about it.... so I figured I'd leave it off since it wound not fit anyway. I, therefore, assumed the other one on the compressor, running away from dryer, was low side.

    My life insurance is up-to-date, so what the hell. I put the adapter (the only one that fit anything) on what I believe to be the low-side off the compressor and I filled it with 2.5 cans of 134a Refrigerant... and got Cool Air!!!!!

    I just did this last night, so I did not know if it will all leak out. Regardless, I'd like to see if anyone else has had similar experiences and maybe some feedback on what I did. If I did some stupid things here, I'd appreciate being told so.... so maybe I won't do them in the future. :oops:

    Sorry for the long post.... I hope someone reads it. Thanks for any input/advice.

    1982 L-Type

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  3. #2
    Boosting Mod SilverMk2's Avatar
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    Mar 2003
    Santa Clara & Stockton, CA
    The high and low ports you want are on top of the AC compressor. The high side one is the closet to the inside on top of the compressor and the low side is the one on the outside of the compressor. If you changed to R134 you should have changed all the system orings and also the oil I believe. If it works you must have done something right though 8) .
    1985 Super Silver Supra 2JZGTE
    2013 Satin White Pearl BRZ FA20
    2001 Black Sand Pearl Corolla 1ZZFE
    "You can never go fast enough....."

  4. #3
    CelicaSupra.com Member CRF_Rider's Avatar
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    Mar 2003
    Portland, OR.
    I bought one of the kits, found that it didnt contain the correct fitting for one side and took it back.

    I still havent put the AC compressor in the car and wont unless I find the correct fittings.

    88 T 5spd SR (SOLD)
    85P 5M-GTE (Now with another owner)
    It's "ORE-GUN" not "ORA-GONE"

  5. #4
    CelicaSupra.com Member trdmkii's Avatar
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    Mar 2003
    Columbus, OH
    I converted my system over r-134a with a kit from napa, i didn't know if mine had a leak or not but i do know that using the leak sealant stuff may clog your evaporator and/or seal things that shouldn't be sealed.....lol, so i went with the kit from napa for 29.95.

    When i opened it up i found 3 fittings. See some r-12 systems had different sized high side ports like ours. I had a friend who i beleive bought the kit that you did and was unable to get his high side on.

    I hooked on both of the fittings and charged it up with the can of oil that they gave me, it blew super cold after i charged it woo hoo, then a week later i put in a toyota reciever/drier that i got for like 30 dollars just to put a new one in, i added oil to it and then recharged it, its been cold for the past 3 weeks with no change, i guess the r-12 just slowly leaked out....

    As for the oil if you use the ether oil instead of the pag oil it will be effective enough and not damage the o-rings and such.

    I found only 3 ports the 2 on the compressor and one by the reciever/dryer (mine is an 85) and i hooked the low to the comopressor and the high by the drier for easier access.
    1985 P-type 5M-GE
    1998 Lexus GS400

  6. #5
    CelicaSupra.com Member Glaucus's Avatar
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    Jun 2003
    Winnipeg, Canada
    Ummm.... I know nothing about how the A/C works on our cars. What's this about oil? Is it mixed with the coolant to keep everything lubricated or is it something used in just one component (compressor?). Just currious.

    - Mike

  7. #6
    CelicaSupra.com Member DKJones96's Avatar
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    Aug 2003
    Albuquerque, NM, USA

    i've serviced plenty of a/c systems myself to tell you just about anything you need to know.

    you should have flushed the system and vacuumed it and put 4oz of new oil in it. that is what all toyotas have used. installed a new dryer, expansion valve and drained the compressor sump.

    the oil for r-12 is NOT compatable with 134a. the mineral oil is too heavy for the 134a coolant to move thru the entire ac system so it'll get stuck in low parts and starve the compressor for oil killing it. the oil also has chlorine in it from the r-12 refrigerant which causes acid when in contact with 134a eating up your air parts just like moisture from the atmosphere that doesn't get taken out unless you pull a vacuume on the system will turn to an acid with r-12 and 134a.

    don't use pag oil. it hardly lubriccates at all. use ester oil i have that on my a/c and it has all origional parts in it basicly except expansion valve and drier everything else is still factory.

    i however don't use 134a or r-12 i don't like either one. 134a is hard on old parts and causes leaks and high pressures that burst hoses. i use es-12a(www.envirosafe.com) it drops head pressure down about 33%. blows much colder air and takes less engine power to run(about 2-5hp). this refrigerant doesn't turn acidic if you don't pul a vacuume and you aren't supposed to pull a vacuume. if your looking for an easier way to fix the ac use this. and find the leak with an ultraviolet leak detector and blacklight. the hose leak will cost you alot more int he long run then the time andf effort to replacce the hose is. this coolant also is reverse compatable with the r-12 refrigerant and is pretty much drop in.

    if your ac blows cold don't bother with the expansion valve(hard as hell to get to). just replace the drier(use ester or mineral oil on the o-rings) tighten it up tight but not toooo tight. and fill it and put a can of oil charge with two cans of refrigerant and boom your done.

    now to answer your questions. the oil is kinda pushed thru the whole ac system. the compressor has a sump which is a small reserve for when the compressor is first started. having the right amount of oil is very crucial. too little and compressor failure. too much and decreaced system performance. the service ports are so plentiful to help with troubleshooting the system. the fat hoses are low side and small hoses are high side(easiest way to remember) liquid on high side and gas on low side. pressures chould be no higher then 250 ont he high side. if it is it's either overcharged or there is a plug(if you do the math when you charge it it'll be a plug garunteed) the low side should be no higher than 45 no lower than 35 at idle and when revved up shouldn't fall below 25. if the low side is low it's prolly undercharged. if it's too high it could be a plugged highside(alot of pressure on the high side) or a weak compressor.

    those conversion kits you buy are crap. seriously that is for a halfassed job that will have to be serviced again sometime soon after that. maybe a few months maybe a year til something dies. i've seen conversions that die after a day of use either because of pag oil usage or they left the old oil in it then again you might get lucky and the conversion may work for years but it's unlikely. if your going to fix the a/c. fix it right.

    i've flushed my system and put a metered amount of oil(4oz) along with new drier and expansion valve(mine was clogged before the conversion) and the right amount of es-12a and on a 100 degree southtexas day i'll get 33 degree air out of the vent after 30 seconds of idle from sitting in the sun about 4 hours.

    one more thing. if you decide to use anything but r-12 don't clear the sight glass. it's overcharged in most cases. the systems in our cars take about 2.5 pounds of refrigerant. that's 40 oz of r-12 refrigerant and 18 oz of r-12 is equal to 16oz of r-134a and 6oz of es-12a. roughly one big can of 134a oil and 2 cans of refrigerant. or two small oil cans and 2 cans of refrigerant. don't use that leak sealing crap those cans are mostly sealer and not much refrigerant in a can and will probably plug up the expansion vlave and drier. just pure refrigerant. fix any leaks by replacing the bad part. and the high mileagecans are shit too.just use normal refrigerant.

    hope this helps. and really sorry it's so long but a/c repair is long and there is alot of information.


  8. #7
    Hey dk tell me about Freeze 12???? I've heard its real good & will cool quickly about the same as your es 12. I had a A/C tech!! tell me it will screw up the system. I don't know to much about A/C systems but willing to try anything once.
    Dick B. 8)

  9. #8
    CelicaSupra.com Member DKJones96's Avatar
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    Aug 2003
    Albuquerque, NM, USA
    freeze 12... i've heardit can be bad for a system but i think most of that is the wrong oil use. everyone should use ester oil. and they don't i bet they put in freeze 12 with pag oil like most conversions "professionally" done are. from what i can see it looks better than 134a but still harder than 12 which could kill already weak parts. i'm not sure tho. but i have heard of it being bad. sorry i can't help much with that one. www.autorefrigerants.com go there and read up on the refrigerants. they have like 3-4 kinds. it does have one plus tho. it isnt flamable.

  10. #9
    CelicaSupra.com Member Rich64N's Avatar
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    Jul 2003
    Tacoma, WA
    How hard is it to empty the compressor oil sump? Do you have to pull the compressor? the TSRM includes this as part of overhauling the entire compressor.

  11. #10
    CelicaSupra.com Member MAD_83supra's Avatar
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    Mar 2003
    Daytona Beach FL
    THank you for the great write up DKJones96

    Now that I know I have screwed up my air system, and why I went through another compressor. How do I purge the system of all the old PAG oil? before I put in the Envirosafe

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