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How Do I Recharge My Ac

Discussion in 'Minivans · Pacifica' started by greg.owen, Jul 27, 2003.

  1. greg.owen

    greg.owen Guest

    I have a 96 Voyager with 3.0 V6 and R134a refridgerant in my AC system. Every 6 months or the so I have to get the AC filled and each time its pressure tested as OK.

    It was suggested that the evaporator may need to be replaced and would cost about a grand to do it as the dash needs to come out.

    Here in sunny florida, the system needs to work. At present it blows cold in the mornings and when kept in the shade but if left in full sun it takes ages to have any effect so I figure its time to top it up again.

    Is it easy for a novice to add coolant? If so could someone please let me know how? Is there any way I can measure the amount of stuff required. I am also interested in whether I can add the dye that would enable me to trace any leak.

    You guys have always helped me before, so I know I can trust you to do the same this time. Thanks
     
  2. Geerhed

    Geerhed Member

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    It is very easy to add coolant, but you have to pay attention so you don't over-pressurize the low pressure side of the AC system (you have to open the valve slowly and 'regulate' it to keep the pressure needle on the fill-kit in the 'green').
    Wal*Mart (and others) sells a R134A re-fill kit (8 - 12oz bottle of refrigerant, plus a fill tube with a pressure gauge and the proper fitting for the low pressure side (it won't fit on the high pressure side so you don't have to worry about hooking up to the wrong fitting).
    Cost you about 10 bucks. Another 4 - 6 if you need a second bottle of R134A. Follow the instructions on the kit.

    If I've given bad info, I hope someone will correct me, but I've been recharging my own AC system for years and haven't screwed anything up (yet).

    Good luck!
     
  3. Geo

    Geo Member

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    Very easy. I have a slowish leak in my 93 Voyager. We have looked everywhere with a "sniffer" and have never been able to find the leak. They want way to much money so I just add refrigerant every summer. There is a valve thing in line, hook up the hose (the one you get from Walmart) and fill her up. Easy. Geo
     
  4. malcom

    malcom Member

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    Yes, go ahead and add some r134a. My 94 needs
    part of a can every month. Technician said the rear
    evaporator has slow leak. :lol:

    Hint: Avoid moisture in the system at all costs. Open
    the valve a little until it hisses and purges the hose of air.
    Attach the hose to the minivan's low pressure fitting while still hissing.

    Recharge with the a/c on high. When it starts to get cold then stop. Don't overcharge.
     
  5. BurnsSide42

    BurnsSide42 Guest

    hi, new member, long time owner :lol: and long time forum person....
    We own a 93 Dodge Grand Caravan 3.3L 121K and running strong, however i need to recharge the a/c but can't locate the low point in the lines....my question is where is it? I found the high point and everything but the low point. THX in advance.
    ~BurnsSide42~ as seen on Saabscene.com Saabcentral.com ifsja.org and much much more!
     
  6. karlStolz

    karlStolz Member

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    Evaporator leaks are very common on 96 and newer DC minivans according to my autoservice instructor, who is a MasterTech at a local dealership in the day. I finished my AC class with him this past May and he was averaging 3 evaporator replacements a week. They also are prone to leaking on the Intrepids too. He said the evaps were rusting at the bottom due to the foam pad that it rested on under the dash. The moisture from the evap puddled up and before long a hole rusted in the bottom.
     
  7. Geerhed

    Geerhed Member

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    Burnside:
    The Low pressure side on your van is the fitting up next to the firewall (beside the computer mounted on the passenger side of the firewall).
     
  8. BurnsSide42

    BurnsSide42 Guest

    are you positive, b/c when we tried that it only would take 1/2 the can......and no more. The system only has enough to kick on the compressor, nowhere near the proper amount. BUT i will check it again to see if that was the only one by the Firewall.....
     
  9. Geerhed

    Geerhed Member

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    You need to have the vehicle running with A/C on Max AC and fan on full when you're adding the coolant.
    Make sure you shake up the can until your arm aches. :lol:

    The fill kit will NOT fit on the high pressure side. However, it does take a little while (10 minutes or more) to get all the coolant in.

    If you're doing all of the above, and you're still not getting cold air (or the AC compressor cycles on and off continuously) your problem probably isn't low refrigerant.

    Unfortunately, the AC systems on cars these days are three parts technology and one part voodoo.

    Good luck!
     
  10. BurnsSide42

    BurnsSide42 Guest

    well we may not have given it long enough to fill...but we did do all that otherwise. I will give it one last shot as soon as the car is back home from work :lol: But if it's not taking the charge like it should, what would u suspect wold cause this??
     
  11. eyknough

    eyknough Abnormal User

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    Karl, thanks for that info. :D

    I'm among the majority of vehicle owners with a/c who have to top off their systems regularly. I have a couple of suggestions, however.

    When the a/c system leaks refrigerant, oil leaks as well. The exact formula for how much and when to add oil is not exact (since all leaks aren't in the same place and same size). But continually adding ONLY refrigerant will eventually leave your compressor starved for oil.

    I have heard that approximately 1 ounce of oil per "pound" of refrigerant replaced is about right. That sounds like a bit much (especially for an evap leak). But I suppose it's better to have too much than too little. At least, I'd pay close attention to how the compressor sounds. If it starts making any noise (mine is virtually silent on my '94 caravan) I'd add an oil charge in short order. (The little cans add 2 oz. of oil and 2 oz of r-134a).

    I strongly suggest getting a pressure gauge that hooks up to the high side ($16 at Meijers here in town). While it's good to monitor low-side pressures for best cooling, it's critical to monitor high-side pressure as well. Factory r-134 systems and legal r-12 to r-134 conversions will have a high side safety cutoff switch (that shuts the compressor off at a little under 400 PSI!!!). Any higher and you're going to blow the safety relief valve in the compressor.

    Keeping the low side in the green while charging is not necessary (that gauge is more accurately interpreted while there is no refrigerant being transferred from the can to the system). The gauge that's in-line with the charge can will experience higher pressures while the hose is transferring refrigerant. The low-side of the a/c system is designed to handle way more pressure than you will produce with charging (as gas) with the valve wide opened.

    Since it's recommended to only charge r-134 as a gas (can upright) it will take much longer to charge. Be patient. If you want to hurry the process, shake the can a few good shakes about once a minute while charging.

    I maintain several a/c systems for myself and family and friends and I actually charge r-134 as a liquid. Never had one bit of trouble. I always have a gauge on the high side and I hold the can in my hand while charging. Monitor the high pressure while you (basically) pour the liquid in. Just watch the pressure on the high side and stop pouring when the pressure approaches about 320-340 psi (but continue to charge as gas) When the pressure drops, 'pour' in some more liquid. It dramatically shortens the length of time for the can to be empty. (Plus you end up with nice cool hands when you're done).

    Get r-134a while you can.... By about 2020 I'm sure the epa (along with money from DuPont) will have r-134 determined to be too dangerous for our planet to endure. Oh... and the patent will have run out too for DuPont. :lol:
     
  12. eyknough

    eyknough Abnormal User

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    Oh. I forgot... lol

    If you absolutely can't get it to charge as a gas, and you're nervous about charging as a liquid with the system running.....

    I have gotten entire cans of refrigerant in to a system that was not even running at all. It took about 5 or more minutes, but if you leave the can upside down, the liquid will work it's way into the system. A good shake about once every 30 seconds will help the process.

    I'd be sure to measure the high side pressure (with the system running) before you add refrigerant like this. You want to make sure it's actually low since you're probably going to put in an entire can without monitoring any useful pressure readings (since the system won't be running).
     
  13. Old Goat

    Old Goat Member

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    I've been recharging mine for the last 3 years or so, but this year took it in to check for leaks and oil in the compressor. Found no leaks and said needed no oil, but I am still concerned a little about the oil. Next year I might add one of the cans that have oil in it. On the shadetree mechanic they were talking about if you let the compressor run low on oil it will start to selfdestruct and then the shavings will contaminate the system. Some can be flushed and some can't very well, at least according to them.
     
  14. 94Grand

    94Grand Member

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    Whew! A lot of ground has been covered in this post already.

    My comments FWIW:

    Be sure NOT TO MIX oil types in a 134a system. Add PAG to PAG, Ester to Ester. Don't mix them.

    Every car or truck A/C I've ever worked on was meant to be gas charged, not liquid charged (although I hear there are/were some exceptions). Most low side test ports are on the direct way to the suction side of the compressor. The compressor compresses gas. Not liquid. Liquid is not compressible. A solid stream of liquid making it into the compressors cylinders is called "slugging". Some kinds of cars have the Accumulator in series, with an internal domed plate to break up liquid, so it mixes in with the hot gas flowing around it from the Evaporator. That can prevent slugging, even if someone tried to do it, depending on the Evaporator temperature of course.

    The charge can cools itself internally when you are charging. This is because the liquid in the can is converting to gas (absorbing a lot of heat, after all, this is the refrigeration cycle!) as you release it into the hose. If this self-cooling of the can is allowed to progress, it will cool to an equalibrium point where the pressure in the can balances the pressure on the suction side. Therefore, no more gas goes in, even with the can obviously having liquid still in it.

    If any of you had chemistry or physics, look up Partial Pressures.

    You don't need to shake the can of 134a to counter this. Instead, place the can in a small bucket of hot water, up to just below the top rim of the can. Change the water if you are doing multiple cans, as it will be cooled off quickly. This is a much better and quicker method.

    And don't shut off the A/C, or the engine once you start charging. At least not with a can tapper valve open. Otherwise, as the system equalizes pressure from discharge to suction, the suction side pressure will rise to well up over what it was while charging. And you do not want to overpressure that disposable can in your hand!! :eek:

    Oh, at least one more........ when using a can tapper, or any hose, always burp some refrigerant gas out of it before attaching to the system. You do not want to blow a slug of air into your A/C system. Did you know that "air" (Nitrogen and Oxygen) is considered an "incompressible" in A/C systems?

    Okay, I'll shut up now ;)
     
  15. malcom

    malcom Member

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    94Grand,
    Nice post. I will put some of it to use the next time I charge the a/c. ;)
     
  16. EXPAT IN MANILA

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    man this Laser printer is fast, thanks for the tips.... ;)
     
  17. zeratulbox

    zeratulbox Member

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    Didn't read all replies but if nobody mention it here it goes.

    dont waste money in UV leak detection additives or buy the can with it... if u did dont bother buying a UV lamp. The thing doesn't work. at least it didn't for me.

    It is best to recharge the system following the instructions from the can. Or recharging kit.
     
  18. Shawn

    Shawn Member

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    Thanks all, for the great info. Here's one more question:
    My van's A/C, at 114k, is working well but I don't know if it has ever been recharged or maintained in it's past. I have this fear that it may quit working any day. Would it hurt to go ahead and add some refrigerant now or should I just wait until I start actually having signs that there is a problem? Perhaps it will either take it or it won't............
     
  19. eyknough

    eyknough Abnormal User

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    Shawn, if your system is cooling fine then don't add a thing. Some times when the system has not needed to be charged you might cause a small leak to start if you hook up the can tap (or even pressure gauge) Well... If it was going to leak, it'd be after you removed the charge hose. Not all systems need topping off every year. My brother has a 12 year old truck with original r-12 system that he hasn't touched at all and it'll freeze you out.

    Thanks for supplementing my post, 94grand. I am not the most experienced person in the world and it sounds like you know more about what you're talking about.

    However I do have a question about the oil compatibility issue you bring up. AFAIK, the oils can be mixed in any combination, but r-134a will only carry PAG or POE. The harm comes when r-12 (from a "converted" system) mixes with PAG oil. You do not want r-12 mixing with pag. Other than that, the POE oil says it's compatible with both retro-fitted and original r-134a systems (which come with pag from the factory).

    I understand that auto a/c systems are supposed to be charged as a gas. R-12 cans say they are to be charged as liquid, though. Sure, r-134a is higher pressure than r-12, but I think if you pay enough attention to the high side pressure you will not hurt the compressor any. For a couple of years I used to charge r-134a as straight liquid, with my hand opening the throttle some to suck it in REALLY fast. The systems are still working now over 8 years later.

    Most people who charge their own a/c systems are using about a 1 foot long hose. Not much room for a container of water under the hood. It's worth a try if it's faster than shaking the can, but I'm happy with the speed of charging as a liquid while monitoring pressure on the high side.

    Stay cool! ;)
     
  20. greg.owen

    greg.owen Guest

    Wow. What a lot of useful information. Many thanks to you all.

    Only 1 last question. Where is the low pressure attachment on the 96 Voyager?

    Keep up the good work guys
     

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