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  1. #1
    jpastaman9
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    Default A/C R-134a conversion- Accumulator installation.

    i am converting my C4 to r-134a and was told that it was probably a good idea to replace both the orifice tube and the accumulator-

    does anyone have any experience with this- it seems pretty straightforward but i read in the haynes manual- something about "525 viscosity regrigerant oil into the new accumulator, plus two ounces"

    any advice or insights greatly appreciated.

  2. #2
    jpastaman9
    Guest

    Default R-12 to R-134a conversion- accumulator installation

    i am converting my C4 to r-134a and was told that it was probably a good idea to replace both the orifice tube and the accumulator-

    does anyone have any experience with this- it seems pretty straightforward but i read in the haynes manual- something about "525 viscosity regrigerant oil into the new accumulator, plus two ounces"

    i have already had the r-12 removed- how important is it to flush the system.

    any advice or insights greatly appreciated.

    thanks

    joe

  3. #3
    marine1975
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    Default

    FYI, if you do not do this properly it will end up costing you a lot more money down the road. It is essential you properly flush out the entire system to remove all the old oil! If you do not get it all removed it will react with the 134 refrigerant and create an acid that will ruin all the other components in the AC system. Usually everything will work fine for the summer and then next year when you turn on your AC you will find that you have leaks in your condenser, evaporator or the seals in the compressor. I will try to find a link to a good site I got a lot of info from regarding converting AC systems and post it later.

  4. #4
    jpastaman9
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    Default

    thanks for the insights- i had the r-12 removed today, and there was some contamination in it- so the tech advised me to remove the orifice tube and replace it, followed by the accumulator before recharging the system- but from your posting it sounds as if i need to flush the system before i recharge it- is this something i can do after i install the new accumulator and orifice tube??

    thanks- joe

  5. #5
    Ken
    Gone but not forgotten Ken's Avatar
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    About the only thing I came up with is the following...
    Actually, very little is required, as long as your compressor, expansion valve, dryer, condenser, and evaporator are sound.

    A good auto technician will be able to check the functioning of the components mentioned and replace those that are malfunctioning.

    We are assuming that the system was functioning before the R12 escaped.

    What needs to be done:
    • Find (any) gas leak(s) in the A/C system and repair
    • Flush system with a compound of Hydrochlorofluorocarbon-141B and Dichlorofluoroethane, which cleans and dries the old oil residue, moisture, and any other junk that may be in the system
    • Completely evacuate the system
    • Install new gas input and output stems. This prevents R12 being mixed with the R134a gas in the future
    • Load the new ester oil into the A/C system. This is compatible with the new R134a gas
    • Load the new R134a gas into the A/C system
    • Change the A/C system pressure & timing settings to accommodate the new R134a gas
    • Place a retrofit sticker on the A/C system stating it was converted to R134a usage
    I know that others here have done the procedure; give 'em some time, they'll respond.

  6. #6
    marine1975
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    The system does need to be flushed before putting in the new refrigerant. I could not find the original site I looked at (about 2 years ago), but I did run across an interesting article that discusses the different "freons" and how they are not compatible. Try this link:

    http://www.autofrost.com/autodisc.pdf

    I have also read in the past where the hoses are different for R-134a systems (new) and the old ones may leak out the R-134a over time. Supposedly this R-406 gets around this issue as well as the compatibility in the oils issue.

    Hope this helps.

  7. #7
    New Member
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    79 L82 4spd

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    Yes, absolutely flush the system. Replace the orifice tube, it is what changes the fluid into gas form by vaporizing it. It also acts as a filter in the system. Any time that you open the system to the outside, you should replace the acummulator (receiver/dryer). It collects moisture in the system & "freezes" when exposed to the outside air. Since it sounds like you're replacing stuff anyway, replace any & all O-rings that you can reach, they are a different material than the R-12 type & will last longer. Be sure to use the correct type of oil for the R-134. Get the stuff that has dye in it, it'll help find leaks in the future. Oh yeah, you DON"T add oil into the acummulator, it goes in the compressor. Easiest way is to pull the compressor & literally drain it. With R-12, the oil circulates thru the system. With R-134, it DOES NOT circulate, it stays in the compressor. Find a screen for the compressor input line so that any residue will not get into it. Personally, I would recommend going to a shop to perform the installation, or, atleast the re-filling & re-charging of the system. Hopefully, I didn't confuse anyone, hope this helps.
    Bill

  8. #8
    jpastaman9
    Guest

    Default R-12 R-134, R-406

    thanks i was starting to lean that way- sounds like recharging is so bad- but the conversion needs to be done by someone who really knows their way around the A/C system- also sounds like perhaps the 406 is the way to go as opposed to the 134- especially if there is a leak issue witht he hoses- sounds like replacing the O-rings is a must. but will keep looking listening-

    thanks again!!


    Quote Originally Posted by BacaBill
    Yes, absolutely flush the system. Replace the orifice tube, it is what changes the fluid into gas form by vaporizing it. It also acts as a filter in the system. Any time that you open the system to the outside, you should replace the acummulator (receiver/dryer). It collects moisture in the system & "freezes" when exposed to the outside air. Since it sounds like you're replacing stuff anyway, replace any & all O-rings that you can reach, they are a different material than the R-12 type & will last longer. Be sure to use the correct type of oil for the R-134. Get the stuff that has dye in it, it'll help find leaks in the future. Oh yeah, you DON"T add oil into the acummulator, it goes in the compressor. Easiest way is to pull the compressor & literally drain it. With R-12, the oil circulates thru the system. With R-134, it DOES NOT circulate, it stays in the compressor. Find a screen for the compressor input line so that any residue will not get into it. Personally, I would recommend going to a shop to perform the installation, or, atleast the re-filling & re-charging of the system. Hopefully, I didn't confuse anyone, hope this helps.
    Bill

  9. #9
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    Yes, you should replace the accumulator. This is standard practice whenever flushing and refilling the a/c system. If you're doing a conversion, a lot of people advise changing all the o-rings in the system because the old rings are "incompatible with R134a". I think I mentioned this before, an ASE-certified mechanic who works for one of my clients claims that he never changes o-rings. He showed me his 1989 Jeep where he did a conversion several years ago without changing o-rings and the a/c is still ice-cold, and high/low pressures never budged. So if you think you need to change them out, go ahead.

    One of the hardest things about changing a/c parts is getting proper torque on the fittings so that the o-rings are seated. This must be done by feel, with two huge wrenches. If you've never done this before, it feels like you're going to break the connection. These parts are all aluminum, so you have to put just the right amount of leverage on it; too little and you won't seat the o-rings, too much and you'll kink the lines. You'll learn pretty fast if you've seated the o-rings after you pull your vacuum to -29, because if the vacuum doesn't hold, you haven't tightened the fittings enough.

    Now, a lot of people disregard a clean condenser when doing a/c. Well, it's common practice to pull and clean the radiator fins on the C4, but the condenser fins also can become clogged with debris over time. It's very important to have proper air flow over the condenser, and when the fins are all clogged with gunk the a/c isn't working to its full potential. When I did my a/c, I bought a new condenser, but you should consider either buying a new one or cleaning the old one. It's pretty easy to remove the fan shroud and pop out the condenser, it might be a good idea to pull both the radiator and condenser and giving them both a good cleaning to get maximum air flow through the fan shroud. Your car will love you for it because it will run cooler.

    Any components that you're not changing need to be flushed with solvent, you can buy it from any auto parts store, comes in a metal can. The evaporator is difficult to change, I read a tip here awhile back about removing the blower fan and looking through the hole to see the state of the evaporator fins, if they look pretty good I wouldn't bother changing the evaporator. Also, you may know that the compressor can't be flushed. Therefore, it needs to be removed and you can turn it upside-down over a small bucket and let the oil drain out, the last time I did this I let it drain for a whole day to make sure I got all the old oil out. When everything is clean, you put two ounces of the new oil in each component: compressor, condenser, evaporator, accumulator.

    At this point, everything is bolted back up, you check all your connections, pull a vacuum, and keep your fingers crossed that the vacuum holds for a couple of hours. If you haven't done this before you'll need a good set of manifold pressure gauges to read your pressures.

    I guess this next part goes without saying, but it's the most satisfying part of a/c work: recharging the system. You close your connections, hook up your refrigerant, bleed the line, and start charging into the low side. Here's a site that might help you:

    http://www.diynet.com/diy/ab_auto_ai...276708,00.html

  10. #10
    photovette
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    Flushing the system is always a good idea--it is a long way from being new. However, I've been running R-409a in my 1977 for three years now--after trying all the others--I used to design and custom build ultra-cold refrigeration systems, so I had about 25 different refrigerants in my shop--and I tried them all. R409a worked the best, and you don't have to get the mineral oil out. My '77, with it's ancient original EEVIR system, can produce cabin temperatures of <60F on a 95F sunny day--most days I have to mix the heat. The only additional improvement I made was installing a evap fan/motor from a '94 'vette.

    http://www.honeywellrefrigerants.com/en/info.asp?id=66

  11. #11
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    Hmm, I just read all the other responses and have to respond to them.

    First of all, I wouldn't use some exotic refrigerant that may or may not be around in a few years, R134a is cheap, plentiful, and will be around forever. The R12-to-R134a conversion is the way to go and if done properly the vent temps will be only a few degrees higher than with R12.

    I've never heard of any a/c system where the oil did not circulate through the whole system. It is standard practice to add oil into all the components, this goes for automotive as well as home a/c systems. I'm looking at my Corvette service manual which specifically says to add oil to all the components. Ask these guys, a/c is all they know:

    http://www.aircondition.com/wwwboard/

    The stock hoses will be just fine for R134a, if they are in good shape and otherwise have no leaks, they will be perfectly okay for R134a and it won't leak through.

    The orifice tube already acts as a tiny screen, I don't think you need any additional screens in the system. If the system has been properly flushed and vacuumed, there is no debris in an a/c system anyway. If the oil leaks out the compressor will no longer be lubricated and tiny metal shavings will circulate throughout the system. This is the only time when debris will be in the system, and by that time the compressor will be making such a horrible racket anyway that you'll know something is wrong. Thoroughly flushing the system prior to vacuuming and recharging will remove all outside contaminants, this is why flushing is so important.

  12. #12
    photovette
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    R-134a has several drawbacks however:

    A higher head pressure than R-12--this leads to reduced fuel economy and increased condensor outlet temperatures. R-409a has a lower head pressure than R-12.

    R-134a is 23% less efficient that R-12 at removing heat. R-409a is 12% more efficient at removing heat that R-12.

    R-409a is not an exotic refrigerant--it has been used by all motor vehicles in Europe for years.

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