Simply want to Add Refrigerant to A/C

Discussion in 'Gen 2 Prius Technical Discussion' started by feivel, Jun 28, 2011.

  1. feivel

    feivel Junior Member

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    Hi All,

    My 2005 Prius compressor probably has a very slow leak. It blows not-so-cold air from the A/C, which started last year. I took it in to have it checked for leaks, and the refrigerant they put in was enough to keep it working wonderfully through this spring. Now it's getting hot and I'm noticing the A/C is not cooling quickly enough. The dealership never found the leak, and naturally wants $1000+ to replace the compressor.

    All I want to do is add some refrigerant, and I expect all will be well again. This shouldn't be too hard, no? And yet all my searching only yields a lot of "it's complicated" answers. So I figured I'd pose the question here.

    Can I buy a can of R-134A that doesn't contain oil, and simply add it to the system? Is it just a matter of connecting a hose from a can, and running the system? Can someone who has done this please chime in with advice or confirmation?

    The only concrete advice I've found pointed to R-134a Hybrid Vehicle A/C Refrigerant Oil Charge (3 oz.) - XXXHYB-2 for oil and refrigerant. But that probably contains too much oil.

    Can someone point to a can of refrigerant that is okay to use?

    FYI, I've also found a manual at http://zeroreality.net/prius/repair/55%20-%20Heater%20&%20Air%20Conditioner.pdf which goes through the whole draining, recharging, disassembling process, but I don't know any reason to use most of it. The system seems to work, just too slowly.

    So I'm asking for concrete, minimal instructions rather than "take it to a dealership." Can you please help? Thanks!
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The simple answer is that yes, you could buy a can of R-134A that doesn't contain compressor oil, and add to the system.

    The complex answer is that if you add too much refrigerant, then you will degrade system performance. Hence if you care about that, you will invest in gauges that measure the high and low system pressure and follow the repair manual instructions. Good luck.
     
  3. feivel

    feivel Junior Member

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    Thank you thank you! Since the dealer is already "offering" to replace the compressor since they couldn't find a leak, I would consider the risk quite reasonable.

    Okay, so let's say I want to do this, can you point to R-134a that does not contain compressor oil or anything that might short out the compressor?

    And yes, I'd love to measure the pressure in the process. Do I need to buy hundreds of dollars worth of equipment, or simply a double gauge and keep the pressures correct as stated in the manual. How much should the process cost, really, assuming I'm not trying to start a business of it?

     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I suggest that you visit your local discount auto parts store and buy a can of refrigerant that is labeled to show it contains no oil. Also buy the double gauge instrument while there, have the repair manual info available (consult techinfo.toyota.com if needed) and you should be good to go.
     
  5. vertex

    vertex Active Member

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    You don't need to buy the double gauge instrument. Many recharge kits now come with a low side gauge, and the can with the hose is around $20. If you want to invest in the high side gauge, the pressure should be 198 to 228 pSI. The gauge you purchase will show you the safe range for the low pressure side.
    Keep the hose only for use on the prius. If you use it on another car, you may then contaminate the prius if you use it on it again in the future.
     
  6. jelloslug

    jelloslug It buffed right out!

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    You can also use the old thermometer in the air vent method. When the air coming out is around 50° F then you have enough refrigerant in the system.
     
  7. S Keith

    S Keith Active Member

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    If anybody else comes across this, hard to beat the site glass method like in the old R-12 days. In fact that's what the repair manual tells you to do. The manifold gauge pressures they give you are almost nonsensical. Simply fill slowly until the bubbles in the sight glass disappear. You'll never get a perfect fill that way, but will NOT overfill it if you stop when the bubbles stop.

    The only way to get a perfect fill is to put the exact amount in, and that can only be done with specialized equipment.
     
  8. ChapmanF

    ChapmanF Senior Member

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    In a Prius (I know this was true for Gen 1, and I believe it stays true for the later generations), the A/C uses a subcooling condenser, which means the proper charge is not obtained right when the sight glass bubbles stop, but when a certain additional weight of refrigerant (100 grams? check the manual, don't trust my memory) has been added past the point where the bubbles stop. So that presupposes you also have a decent postal scale or something to have your refrigerant can on, so you can tell when the specified additional weight has gone in.

    You should also make sure you do this under the exact conditions stated in the manual (surrounding temperature within the given range, doors open, fan speed as stated, etc.) ... conditions that are too different can change when the bubbles disappear, or they might not disappear at all if the weather is too hot, which would lead you to overcharge.

    I am not looking in a Gen 2 manual at the moment (I've used up my techinfo days for now), so anybody with the manual handy, please do fill in more details, or correct me if I'm wrong about something ... I'm going by what the procedure was for Gen 1.

    -Chap