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How Do I Recharge My Ac

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

  1. gusc

    gusc Member

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    I assume that your good pressures were after adding freon. In that case your system is probably good. If pressures are good before adding freon you don't need any more.

    Adding too much will actually result in decreased AC performance and higher temps!! A good system will usually give 37-48F at the center AC outlet on the dash in 90F temps, colder when temps are lower.

    Pressure at the charging gage should be 37-45psi at 90F with the valve at the can CLOSED, this will give the actual system pressure. With the valve open you may get the can pressure instead. This has already been posted but is very important.

    Don't ever shake the can unless you are adding oil in which case read the directions. Shaking can introduce liquid into the system, bad! There are some good instructions posted here, shaking the can is not one of them.

    Make sure the engine is running at a fast idle, not slow idle. Only connect the can when the AC is running and at fast idle unless the system is completely empty.

    NEVER connect the can when the AC is not running unless the system is completely empty, especially when it is hot or at high pressure from running. These high pressures can blow out the can.
     
    Dave Z likes this.
  2. ka9yhd

    ka9yhd Active Member

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    If you want to hurry up the process, you can warm up the can by putting it in a bucket of warm water to turn the liquid inside the can to a gas. And keep the can upright.
     
  3. jafo

    jafo Member

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    I'm guessing my 96 might be one of those 'thin-walled' condensers and maybe that's where I should start my leak search.
     
  4. gusc

    gusc Member

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    Finding leaks is major frustration, you have my sympathy!!

    My favorite leak tester is the dye/infrared light system.

    I never was able to make the sniffers work, too many things under the hood cause it to react.
     
    jafo likes this.
  5. jafo

    jafo Member

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    Actually found my leak by pure chance. Took off the low pressure cap to add 134a and saw it bubbling. Got a $2 tire valve tool and that seems to have fixed my loss of refrigerant.
     
  6. gusc

    gusc Member

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    This is the most common problem I have had with ACs in the past 2-3 years as well as the tire valves on my large RV tires.

    My wife's '89 Cad is now having the same problem. It is annoying because it requires losing all the freon to replace this tiny, cheap part.

    Makes me wonder if we're getting inferior valves now?

    I can understand why high pressures and heat are hard on AC valves but tires don't have such problems.
     
  7. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    Tire valves don't see 300 psi or the chemical and heat exposure that the A/C system does.
     
  8. jstew314

    jstew314 Well-Known Member

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    It seems there are high side and low side devices for changing a/c Schrader valves without discharging the Freon in the system. http://mike-thomson.com/blog/?p=1234.

    It is surprising to me that the integrity of the system would depend on Schrader valves. I would have thought that the Schrader valves would be isolated by positive closure sealing valves on the system sides, but this is probably too costly or maybe it would not work for some reason.
     
  9. gusc

    gusc Member

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    js,

    Thanks very much for the link, didn't know such things existed. I've delayed changing slow leaking cores many times.because I hate to evacuate systems.

    The caps are supposed to hold pressure if a core leaks, but some do and some don't. They all have "O" rings in the head of the cap so I don' see how some leak. I could understand a hi side leak but my leaks have all been on the low side? Maybe because it is used more?
     
  10. Rick Anderson

    Rick Anderson Well-Known Member

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    Some just have a flimsy rubber sheet for a seal in the cap, the caps are flimsy plastic that would blow right off if exposed to the 90 PSI that most system have while static.

    That would be a good aftermarket item, a quality aluminum or at least stronger plastic cap that seals well, the bosses on the lines for the valves are strong enough to seal, its the cap that's weak.
     
  11. TaxiGirl

    Level 2 Supporter

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    Where does the freon go when you evauate it using your venturi method?
     
  12. ImperialCrown

    Level III Supporter

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    It goes into the atmosphere, which is illegal and just plain bad practice if you are an environmentally-conscious, certified A/C tech. You also lose the charge and can't re-use it. It is best to reclaim the old refrigerant into the tank and recycle it.
    I don't recommend Tweety Bird's method.
     
  13. Rick Anderson

    Rick Anderson Well-Known Member

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    I think Tweety Bird was talking about drawing a vacuum on the system by using a cheap venturi vacuum pump that uses compressed air. A vacuum pump for AC would easily cost $100 and usually much more. If you have an air compressor, you can get a $8 venturi pump that can draw a vacuum. True, its NOT nearly as good as the conventional vacuum pumps. But if you only need it once in a while, and are smart enough to innovate and adapt, you can draw a vacuum on the AC system just fine. It may take more than the 1/2 hour a conventional vacuum pump you leave running will take, but you can get there.

    Tweety Bird used the term "evacuating" the system, when he should have used terms like "draw a vacuum" or "vacuum down the system", that could give you the impression he was talking about drawing out the refrigerant using the venture pump. I don't think he meant that, and when I have used the venturi pump, it was on an empty system that I did AC work and thus needed to draw a vacuum for 30 min before servicing it myself using cans of R-134a.
     
  14. Rick Anderson

    Rick Anderson Well-Known Member

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    TaxiGirl, remember on your other thread about AC, you said you saw bright florescent ooze bubbling from one of the service ports. That likely is the dye leaking out with the refrigerant and the leaking refrigerant, as well as it evaporating as soon as it leaks, is causing the dye to bubble. That is a leak you will need to take care or your AC system will NOT work right.

    What I think jafo is saying, is he got one of those $2 tire valve tools that is used to remove and install new Schrader valves, and he used it to tight down the existing Schrader valve and that is all he needed to do to stop the leak. The Schrader Valve is like the ones in tire valve stems, they screw in and out of the valve stem, same for the AC service ports. Although I suspect they use a different valve designed for AC and NOT just tires. Its possible the Schrader valve itself backed out of the threads a bit, unsealed and that is causing the leaking. Thus if you have the tool you can tighten it and see.

    If you remove the Schrader valve, while the system is charged, all the refrigerant will vent to the air, and as it expands and evaporates, the area surrounding it will drop to way below freezing temperatures and could cause frostbite injury's, as well as the high pressure gas venting could be dangerous.

    The "proper" way to replace the Schrader valve, if you've checked it just wasn't loose by trying to tighten it and see if that fixed the leak, would be to recover the refrigerant using expensive tools designed to do it, or take it to a professional that has the tools. Change out the Schrader Valve with an AC Schrader Valve, NOT a tire Schrader valve, it may fit and work, but probably for only a short while. Then reservice the system, filling it to full it to the proper charge.

    Yes, folks have just vented the refrigerant to the air by simply depressing the nipple on the Schrader valve, like you would let air out of a tire. Although the chances of getting caught are pretty darn slim, its illegal, that's all I'm going to say about that.

    I doubt your only problem is a leak from the Schrader valve, the bubble you see is probably a sign you have one more leak at least. The Schrader valve is opened during servicing, and you have problems servicing the system, so something else has to be wrong, cause if it was the Schrader valve, then your AC system would service just fine and take a full charge, and its NOT, cause the Schrader valve it taken out the picture completely when you hook up the gauge connections.
     
  15. hkusamdoc

    hkusamdoc New Member

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    Enjoyed reading through this thread. I have 2005 GC modelSE with a/c not cooling. My wife took to mechanic who said cannot be recharged. Is this the r-134a system ? Any suggestions ?
     
  16. ka9yhd

    ka9yhd Active Member

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    Hello and welcome to the forums.
    Yes your 2005 GC is using R134. I believe they made the switch from R12 to R134 in either 1993 or 1994.
    Did the mechanic say why it can not be recharged? We need more info as to why it can not be recharged to offer help.
     
  17. hkusamdoc

    hkusamdoc New Member

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    Thanks. I will talk to the mechanic who tried to recharge the a/c. I also have 2 other GCs 2006 base and 2006 SE, so I am also preparing for possible a/c maintenance on these. I have found two ports in the a/c tubing. One is near the radiator on passenger side and I am guessing that this is the return line to pump. The other port is above, near the air filter. There is a bulb component just in front of this port.
     
  18. ImperialCrown

    Level III Supporter

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    If it is empty of refrigerant, then you have an A/C system leak.
    Look for an oily spot of phosphorescent green dye left behind.
    You need to fix the leak first and not just recharge a leaking system.
     
  19. hkusamdoc

    hkusamdoc New Member

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    I have never noticed a coloured leak, but for several years the car drops water in the garage after parked. I had thought this might be ice melting from the a/c expansionchambers. Could this be related to an a/c problem ?
     
  20. Rick Anderson

    Rick Anderson Well-Known Member

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    A proper working AC system should not form Ice, it should stay just above freezing temp to avoid parts icing over. Icing will block the air flow and since ice expands it can damage metal parts.

    The just above freezing temp evaporator, will form condensation on it from the air blown through as that air cools. The water from condensation will drip down into a pan and drain out. So seeing water drip on the ground from your vehicle after using the AC is very much normal.

    There are several spots in the AC system you can NOT see, so if the leak is in those unexposed areas, you could have dye leaking in there and just not see it. The evaporators are common sources for leaks, and they are buried under the dash or under interior trim in the rear of the vehicle if you have a rear AC system as well. Perhaps, dye from a leak might mix with the condensation water draining out of the evaporator cases, if you do see dye in the water that dripped out of the vehicle, that is a big sign that the leak is in the plumbing or parts in the evaporator case.

    I also had a AC leak, used Dye when recharging, never saw dye anywhere, from the other symptoms I figured out it had to be an evaporator leak. When I finally did all the work to get the evaporator box and out and open it, sure enough there was a ton dye in the bottom of the evaporator case.
     

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