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Refrigerant Replacement

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by C-in-DC, Apr 10, 2023.

  1. C-in-DC

    C-in-DC Member

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    I’m getting 2000 to 3000 rpm on the compressor this morning with a setting of 68 on auto and about the same psi. It’s 68 f here. No real need for Ac. It does feel good though even it’s only for testing.

    @lech auto air conditionin in terms of readings, is there anything I should keep a look out for that tells me I’ve charged the system incorrectly? Or if moisture is in it? If I added too much oil? I’ve seen other threads where you say you can hear when the compressor is overworking. With the amount of experience you have I bet your ears are tuned to hear such.
     
  2. lech auto air conditionin

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    Unfortunately, due to the variable speed, compressor and the sensors will try to compensate for anything that is wrong if it’s minute.
    At low ambient temperatures if you’re a little overcharged, you will not know it

    If it’s a Little, a Under charged, you will not know it

    If you have a little too much oil or too little oil, you will not know it

    If you have moisture, you will not know it

    They will cause problems at higher temperatures

    in the terms of
    metallurgy leaks are called in caused by formicary Corrosion. This is when the acidic nature of the oil that has mixed with moisture in the air at a microscopic level literally bore tiny holes through the metal just like beetles or bugs or termites eat tiny holes through wood.. many of these leaks that we see on our condensers and our evaporator’s that are not actually cracks or failed braise joints.

    that appear in the center of our refrigerant tubes are caused by this an automotive technicians don’t know this they just say it’s a bad component. There’s a vast difference between a crack failure by stress, whether it be cycles of hot and cold or physical stress..

    And on the microscopic level of formicary corrosion caused by lazy technicians, who believe it’s OK to leave lines are open to the air. Atmosphere that saturated with moisture.. you shop compressed air to look for leaks that is extremely saturated with moisture. And those stupid little filters that you use for paint or even the small desiccant ones do not remove enough moisture to make a difference because we’re talking about parts per million in contamination.

    This all causes damage over a long period of time, nine months, 18 months, two years. It’s eventually a guaranteed ticking time bomb that cost customers lots of money..

    And many automotive technicians from old school or in denial they’re like ostriches, bury their heads in the sand. And say they done hundreds or thousands of air conditioning systems and leaving moisture in the system using shop here and they all works fine when they leave their shop..

    Any child eight years old with a hose in a can can do the same thing so that’s not too impressive.

    But this is the problem with our automotive trade. The lack of education is absolutely staggering.

    In the pigheadedness and stubbornness of denial because they can’t see things with their eyes that they’re not the cause of the problem is another big problem in our industry.


    So the answer to keep it short
    No, you’re not going to see anything on your software that’s going to show you any problems at low ambient temperatures with minor contamination of air, and or moisture and or over or under charge.

    It’ll happen over a long period of time.

    It’s really simple

    If you only charge by weight and you do it (“CORRECTLY”!).
    Anybody can use the scale and say they use a scale, but made slight mistakes and get it wrong still.

    Even if you have a cheap vacuum pump and not the best set up as long as it’s sealed as a do it yourself person in your own home there’s no harm in leaving your vacuum pump on for 24 hours. Because a person who does not on a micron gauge cannot tell whether or not they pull the complete and good vacuum.. so as long as there’s not leaks 24 hours is a pretty good, 99% guarantee of at least getting it halfway right.

    That’s why there’s a difference between compressors that out, live the life of the vehicle outlive the life of the transmission outlive the life of the engine.

    Because compressors don’t die, they are murdered

    Wait to hear an update on your first day you get to use this vehicle driving down the highway at 100°F plus weather to see what the temperature coming out your dash is.
     
  3. C-in-DC

    C-in-DC Member

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    Well that’s a chilling response. Pun intended.
     
  4. lech auto air conditionin

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    Pun accepted
    There’s a reason they call me cold finger.

    But I usually go by Thermal Alchemy
     
  5. C-in-DC

    C-in-DC Member

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    Good ones!

    Maybe I should get it recovered and try again. I don’t mind leaving it on the vacuum pump overnight if I can close the hood somehow. Charging it again would be a good lesson for me.
     
  6. lech auto air conditionin

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    if the cost and expenses not too much for you, just make sure when the refrigerant is recovered it’s recovered very slowly on the low side suction. So as to not remove any oil..

    Be good practice for you and just leave it on the vacuum pump overnight.

    But the absolute most important thing is a spot on refrigerant charge.

    One or 2 ounces make a real big difference on a Prius on a 95 or 100+ degree Fahrenheit day.

    On a cool day, anybody can squirt in refrigerant and make it come out nice and cold out the dash being overcharged or undercharged this happens every day all over the place.?

    It’s that preciseness that is important for longevity and maximum performance.
     
  7. lech auto air conditionin

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    There’s a little bonus video to watch

     
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  8. C-in-DC

    C-in-DC Member

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    Checked around, can’t afford the recovery. No rental equipment available anywhere either. Stuck.
     
  9. C-in-DC

    C-in-DC Member

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    I haven’t watched the video yet but thank you. Friend of mine is letting me borrow his recovery machine.
     
  10. C-in-DC

    C-in-DC Member

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    @lech auto air conditionin I recovered the refrigerant in a 30 lb tank. Plan on charging the system again with a new 12 oz can tomorrow After leaving the vacuum pump on overnight.
     
  11. C-in-DC

    C-in-DC Member

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    12 oz= 340.194 grams = .34 kg. System takes .42 kg (min) to .52 kg (max). That means I undercharged the first time but the code went away because I got to a minimal threshold.
     
  12. C-in-DC

    C-in-DC Member

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    I left the vacuum pump running for about 9 hours. Closed the high side and low side valves at the manifold gauge. Connected the 12 oz canister of R134A to the yellow hose after disconnecting the vacuum pump. I opened the valve tap on the canister. Next step I copied from a video was to bleed the hose out by turning the canister upside and allowing some liquid to come out of the bleeder valve on the manifold. I got Vapor right away instead. Probably mistake one besides not listening to @rjparker about letting a professional do it.

    The canister was placed on a digital scale and weighed a second time to get the tare right. Opened the low side valve at the manifold and immediately saw the psi on the low side gauge jump up to 100 or so. High side gauge went up to 120.

    The vacuum wasn’t strong enough to continue pulling in the refrigerant so I started turning the canister at 90 degrees and back upright. Periodically, I checked the canister on the scale.

    So here’s where I probably made a major mistake. I decided to turn the car on and ac to get help from the compressor with pulling the refrigerant in. I did this and emptied the first 12 oz can Ie 340 grams.
    Low side psi dropped to 30 but high side went up to 200.

    the low side valve was closed again and I disconnected the yellow hose from the tap valve. Unscrewed it from canister 1 and put it on canister 2. Weighed canister 2 to get the tare. continued to run the engine and ac. The yellow hose was bled out and 127 grams was added from canister 2. Total refrigerant was 467 grams or .467 which is kind of between .42 and .52 kg. I let the car run for a half hour with ac on max ie low setting. The psi levels did not change much. Checked the rpms of the compressor and found it around 7000. Outside temp was about 93 degrees.

    I felt the refrigerant lines on the car. Mind you I have no idea what I’m doing. High side was warm to the touch and low side was cold. This leads me to believe the expansion valve froze.

    I decided to drive around a bit and read the rpms of the compressor and coolant temp to see if the compressor was going to burn out like glass joe from Mike Tyson’s punch out. The rpms went down to about 5000. Before heading out, low side read 30, high side read about 200. I disconnected the manifold gauge and some black oil or something splattered out. Also had tons of pressure on the high side connection.

    gonna go back to the manual to see how bad I messed up. Good lesson but when the compressor dies I’ll probably regret it all. For now will just leave it as-is.
     
  13. C-in-DC

    C-in-DC Member

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    curious. Now it’s reading low side 101 high side 102. Maybe I didn’t mess up?
     

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  14. rjparker

    rjparker Tu Humilde Sirviente

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    The question is does it cool and what is the air temp coming out the middle vent? On a variable capacity compressor you can't judge by the pressures.
     
  15. C-in-DC

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    I don’t have a thermometer but from my experience it’s blowing the same as when I first bought the car. I’m really surprised. It’s also blowing dry cold air. When I tried the first time the air felt cold but humid so it probably still had moisture in it coupled with a low charge.

    I guess I’ll buy a cheap harbor freight thermometer and check. To be continued….
     
  16. C-in-DC

    C-in-DC Member

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    I understand the Txv to be like an equal sign in a quadratic equation. The system psi will read the same on both sides if there’s no clog at the expansion valve. Is that only an antiquated concept from non-hybrid pre-electric compressor systems or is that just a flat out erroneous understanding?
     
  17. rjparker

    rjparker Tu Humilde Sirviente

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    A txv reduces pressure as it meters liquid refrigerant into the evaporator. When testing variable capacity it has to be run at max cool, high fan in a hot environment (86-95f) with the doors open. You should get a decent subcool value using realtime temps into a digital manifold like Tom uses. At that point pressures may be more typical. If its not broke don't fix it.

    Weighing in a charge is the gold standard in any system but is critical on systems used in these cars and minisplits. Performance based on vent air temps under hot conditions becomes the easiest test.
     
    #117 rjparker, Aug 12, 2023
    Last edited: Aug 12, 2023
  18. C-in-DC

    C-in-DC Member

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    this equal reading on high and low side was with the car off. Tomorrows high is 93F, could I read the temp with an infrared thermometer or does it have to be the field piece type with an orifice?
     
  19. rjparker

    rjparker Tu Humilde Sirviente

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    I would get something like this locally or from Amazon. Infrared is ok but you are then measuring the plastic vent and not the air. Measure while in recirculate, max, idealing driving.

    IMG_2569.jpeg
     
  20. C-in-DC

    C-in-DC Member

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    . At one point it got down to 40 when I was on the highway. I think @lech auto air conditionin usually gets his down to like 35f if I remember correctly. It’s 90f here.
     

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