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Fix A/C or Live Without? ;-)

Discussion in 'Gen 2 Prius Technical Discussion' started by Robert John, Aug 13, 2021.

  1. lech auto air conditionin

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    I personally like to play with stuff just to do it for fun even if it’s going to cost me more money than if I paid somebody else

    I have not TIG weld since college, Are use Oxsee acetylene on a daily basis I braise with Silver I Solder with lead (I like lead it taste sweet in your water )

    Circuit board level repairs with SMD with Leaded Solder.

    I’m going to be building a lumber rack on my 2012 Prius C and modifying my trailer hitch 282 inch receiver for a bigger trailer and or a mobile carrier so I could wheel up some of my bigger recharging recovery equipment multiple units on the back of my vehicle.

    So I will be purchasing a TIG welder and all the accessories that will cost me more or the same close to.
    Just because I want to get back into TIG welding and MIG welding for DYI hobbies in my work I’m tired of relying on other people businesses and companies that are unreliable

    I have had people contact me on my Internet YouTube channel and ask me for a list of equipment that cost them well over $1000 or $2000 just so they can do their own air-conditioning on one car. Because they were tired of the local garages screwing up on the air conditioning.
    We would email back-and-forth text message back-and-forth and even FaceTime back-and-forth walking them through each step how to hook up the equipment and recharge correctly to come out with a good result.

    These are people who are not mechanics one person was even an airline stewardess who owned a very nice older BMW very high-end very rare in excellent show room condition.
     
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  2. Robert John

    Robert John Junior Member

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    "Yes, if you open the system to to replace a bad O ring (hope there isn't any corrosion in the fittings) then you do HAVE to evacuate to system before charging. Air in the system will cause all sorts of havoc if you try to just "charge and go". You might be able to have a local shop do an evavc and charge for you if you do the repair work."

    Thank-you for a very thorough reply. Your videos are extremely educational – most useful in helping me address the A/C leak myself. If I was within a day’s drive of the Bay area, I’d bring my Gen 2 to you, but unfortunately, I have to rely on local resources here up north, out east where auto A/C shops here hear cash registers ringing when a car comes in with an A/C problem. I 'd like to avoid being charged more than the car is worth to replace (what may be) just one leaking ‘O’ ring. I’m retired, so this 2008 Prius is a ‘project’ car, not my daily driver. I enjoy mechanics, learning about hybrid systems (and now A/C ;-), and hope to use it as my ‘summer car’ (a low-riding FWD car is not practical here in the winter.)
    1. With the bumper (and all upper & lower shields) off, I had access & opportunity to thoroughly ‘leak-hunt’ with UV, a sniffer, and soapy water – following all the recommended protocols (once again, thank-you!). And, as mentioned, the flange on the low-pressure input to the compressor is (so far) the only culprit, confirmed by all three methods.
    2. I appreciate that it would be ideal to recuperate the old refrigerant, but given that the system is at stasis (0 psi), that horse has already left the barn.
    3. I have three questions: one ‘theoretical’, three practical:
    Q1: With a vacuum pump connected to a closed system comprised of an extensive length of narrow diameter plumbing, how do all/most nitrogen, oxygen & H2O molecules travel through a closed system to the vacuum draw point?
    Q2: When evacuating a system with a vacuum pump, is the vacuum concurrently applied to both the H&L side via the manifold gauge set? Or to just one of the sides, and if so, which one?
    Q3: The Toyota Gen 2 Prius shop manual specifies the amount of refrigerant to charge the system with; correct recharging procedure; H&L pressure ranges under different conditions; etc. But I haven’t found how much POE oil to add after evacuating the system. I’ll be lubricating the new ‘O’ ring & flange with ND-11, and intend to use an A/C POE oil charge aerosol to replenish the evacuated oil. Aside from using inexpensive air conditioning oil ‘testers’ to measure & adjust the amount of oil post-facto, is there a ‘rule-of-thumb’ for how much oil should be added after evacuating a system (in which the compressor was not removed or serviced)?
    Q4: In my situation (replacing one 'O' ring), would you recommend replacing the desiccant bag in the condenser? I haven’t seen much discussion on this.
    Thanks again for sharing your expertise – comprehensive and very much appreciated!
     
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    Just editorial: if you select someone's text, a little green box will appear on the lower/right corner:

    upload_2021-8-22_12-47-32.png

    Click on reply, and the selected text, with a note naming the author, will be added (an example at top of my post). That way everyone knows who you're quoting.
     
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  4. ChapmanF

    ChapmanF Senior Member

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    Brownian motion, calculated with a very low probability of molecules re-entering from the vacuum draw point.
     
  5. Robert John

    Robert John Junior Member

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    Mendel Leisk
    Got it... thanks for the tip!
     
  6. lech auto air conditionin

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    Q1. There is a very tiny insignificant amount left in the furthest regions that do not get drawn out. You get to a point they called molecular state where there’s no more substance to be pulled out to sweep the moisture molecules or anything that is just sitting in hovering on the surface of the inside of the pipes.
    This is where when somebody really wants to get extreme like in Laboratories for when I’m performing a procedure called (triple evacuate and hers with dry nitrogen. )

    After evacuation can you hook up your nitrogen tank to the hi side fitting.
    You open the valve and you purging just enough nitrogen to bring it up to about one psi.
    Can you repeat evacuation on the low side until you’re down to under 1000 µm
    Go back to the high side fitting open up the nitrogen bring it back up to 1 or 2 psi and repeat this procedure three times.

    Every time you bring it to a very very low vacuum you bring some of the moisture that’s contained in the surface of the oils and metal pores up and out to the surface walls of the pipe.

    But because at the very end you run out of mass of material to perform a sweeping or pulling action it just sits there. And this is where the sweeping action of providing a dry gas to come in behind it and push it like a flash flood to the other end which would be the low side


    Q2. After performing the Triple evacuation and nitrogen purge hook up both sides of fittings to vacuum pump and just leave it on overnight.

    Q3. No oil is removed during the vacuum procedure. So there is no need to add anymore.

    unless you were replacing a part like a evaporator or a condenser

    or the desiccant bag sock in the condenser which I recommend you replace which answers question number Q4

    and if you discover any small shaded dark spots on your condenser the size of a dime a quarter or a silver dollar that appear to accumulated a little dust on them then you would change the condenser which already have a new desiccant sock inside of it. Should I believe Toyotas tiny little oil bottle that comes in the OEM DENSO box with the condenser has 40 mL of ND 11 POE oil
     
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  7. TMR-JWAP

    TMR-JWAP Senior Member

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    You should visit the HVACtalk.com forum and explain this about the triple evac. Seems to be a topic over and over. Some swear by it, some think it's a waste of time. Personally, I have the time, material and equipment, so I do it. I don't recall having seen anyone there explain it quite so clearly. Maybe it would help some guys get their head wrapped around it.
     
  8. lech auto air conditionin

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    It’s extremely grammar school level simple I don’t know why the forms have an issue over this topic that is debated.

    If anyone owns a good quality micron gauge and has the experience and know how to actually understand measure read catalog and comprehend what it’s telling you.

    Then that person can actually see the difference every time they sweep with nitrogen.

    Now under the most ideal perfect laboratory conditions. Do you have a evaporator that’s brand new not open to the atmosphere yet brand new dry clean line set that has never been open to the atmosphere you’re just connecting two lines at the evaporator two lines at the condensing unit with 100 feet of line set that you just opened up 10 or 15 minutes ago. That was perfectly dry in the first place.

    And if you have a good vacuum pump not using refrigerant hoses but using a copper metal line as your vacuum line or something like the silicone hoses BluVac you will not measure see or read much of a difference because everything is perfect to start with. But there will be some benefit to most people they don’t care. But I’m kind of OCD like that I go through the procedures anyway even on brand new equipment. But then if you seen my YouTube video on a 20 ton LG Multi V attached are three air handler’s two 6 ton units and one 8 ton unit had the vacuum pumps at one end of the system the micron gauge at the other end of the system and got it down to 10 to 13 µm.


    then you have a situation where everything is new you put in but if you have multiple joints like hard ACR with lots of elbows and the line is outside the building goes through a wall inside the building and either the building is high humidity or the outside is high humidity then depending whether the building is under a negative vacuum pressure or a positive pressure you’re literally blowing the outside atmospheric humidity air is flowing through your pipes as you are laying them down. As fast as that humid air is flowing over the perfectly dry metal and metal is as porous as a sponge that you sop up water on the sink.

    This is where the triple VAC and nitrogen sweep have much benefit.
    And on old used dirty systems

    been on Hvac-talk forms I’m signed up over there haven’t been on there in a long time
     
  9. pasadena_commut

    pasadena_commut Senior Member

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    There are things a lot worse than the Prius A/C. Try working on ultra low vacuum applications sometime, where building a system that will hold the desired vacuum is a massive PITA. A single fingerprint on the inside of the chamber can ruin the vacuum, for all practical purposes, forever. Here is a brief overview of some of the issues:

    UHV Basics
     
  10. lech auto air conditionin

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    Yes my father taught me about ultralow vacuum and things like fingerprints and even certain metals Ofgas just like rubber as if they were a permeable surface.
    Who would ever think that a metal under a ultra long vacuum starts offgassing the metal itself not contaminants.

    The world of ultra low vacuum is that a whole Nother level

    Guys who own reciprocating vacuum pumps have no idea what vacuum really is and how much energy and power is required to get down there

    let alone the measurement equipment required to take those type of management is not your analog or digital every day micron gauge we use an HVAC.
     
  11. Robert John

    Robert John Junior Member

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    Success… I think.
    a) Fixed leaking flange on compressor; b) Applied vacuum (-26 psi) for 50 mins; c) Shut-off vacuum, -26 psi held overnight but applied vacuum again for 50 mins (to suck-up any more wandering molecules ;-) d) Filled system w/ R12a to 30 psi before starting compressor; e) Started car: doors & windows down; A/C on ‘Max Cold’ & ‘Recirculate’, fan on ‘High’ (as per manual); f) Fed R12a into ‘Low’ side of system; g) L-side gauge climbed way-up, then settled down at 30 psi (manual says 21.3 to 35.6 psi); h) H-side gauge climbed to 115 psi (Too low: manual says 199 to 228 psi.) R12a refrigerant operates at a lower head pressure than R134a (manual's refrigerant), but 115 psi seems too low; i) Temp on air vent dropped to 40.8° F (ambient temp 65° F); j) Tested L-side with oil tester (hard to read). Appeared to be a bit ‘low’ so added some ‘Oil-Charge’ (refrigerant + POE oil in aerosol can); k) Ran A/C again, still reading L:30 psi, H:115 psi.
    The conundrum: Emptied entire can of refrigerant into the system (680g eqv. of R134a). Manual says (after vacuum), charge system w/ 450g +/- 30 g R134a. (I assume that doesn't take into consideration gauge hoses.)
    Diagnostic videos & Prius shop manual don’t have ‘L:OK, H:low’ scenario. Conditions closest to this (L:low, H:low) suggest ‘insufficient refrigerant’… but I’ve already loaded 200g more than the manual recommends, plus a bit more with the refrigerant+POE oil. Also, Prius shop manual psi references are at 85° F, my re-charge was done at 65° F… 20° lower.]
    Sooo… I’m hesitant to add more refrigerant.
    Any observations and/or suggestions for this A/C newbie appreciated.
     
  12. lech auto air conditionin

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    I think about 12 more pounds of R12 should make it colder because we all know more is better. Just joking

    can’t quite remember but does POE aerosol oil injecting cans. Their quantity is it 2 ounces of liquid lubricant ?

    and what is the Prius total system capacity 2.77 ounces to 3.7 ounces ? Something like that ?

    But I guess it has Too much oil it will be more slipperier and the compressor will spin faster easier
     
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  13. Robert John

    Robert John Junior Member

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    Thanks for GBTM...
    1. The POE oil+refrigerant aerosol can is 4 oz (113g) I added some, not all, but have no way of measuring how much. I’d guess approx.. 1 oz. (30g)
    2. The Prius shop manual doesn’t specify the capacity of the A/C system, only says to charge the system w/ 15.9 oz +/- 1.1 oz (450g +/- 30g) of 134a after vacuum purge (I'm using 12a). It also states “…approx. 3.53 oz (100 g) of refrigerant may need to be charged after bubbles (in sight glass I presume) disappear” That would be a possible max. total of 20.5 oz (580g). I added a whole can of 12a (680g eqv. of R134a) plus a bit of the POE oil+refrigerant.... with those little oil testers, it's hard to tell if I should add more.
    3. The system is cooling great (40.8°F), but the low H-side pressure (115 psi) is puzzling me... I'm hesitant to add more refrigerant and risk over-charging the system.
     
    #33 Robert John, Sep 3, 2021
    Last edited: Sep 3, 2021
  14. pasadena_commut

    pasadena_commut Senior Member

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    Buy a digital food scale with around 0.1 oz accuracy. Here is the first one that popped up on Amazon in a google search:

    Edit: URL won't post. Paste this into google search to see the one I mean:

    site:amazon.com "Kitchen Scales, Accurate Weight Scale"

    You weigh the can full, then use it, then weigh it again. The difference is the amount of injected oil + refrigerant. If too little was put in, add a bit more. Just don't go too far, since there is no way you can reverse the process. Caveat, if the can cools significantly water may condense on the outside and throw off the later weight measurements. In that case you might need to let it warm back to room temperature so that the condensed water can be wiped off and not immediately reappear.

    This sort of weight difference measurement is pretty common. For instance, when fumigating a house they often hang the cylinder of poison gas from an overhead scale mounted on the truck and let a set amount out by weight.
     
  15. lech auto air conditionin

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    Man I have been really brain dead and didn’t pay close attention to what refrigerant you were using I usually read and comment on this post while I’m driving. Or late at night passing out tired.

    You’re not installing R12. You’re installing the propane butane 12a. I forgot about the stuff I made a video on it.

    I remember almost a dozen years ago the place that manufactures those little cans of 12 AA blew up because they had a leak in the refilling process and blew the roof off their building.

    And then I believe just recently several months ago they had another explosion that blew their building up.
    It must be some newfangled marketing scheme for selling their product to put in the car. ???

    especially Prius is that have the highest rate of evaporator leaks when they get that old.







     
  16. Robert John

    Robert John Junior Member

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    Thanks again to everyone for the comprehensive support & advice. I have a few things to add:
    1. Re: Pasadena_com mut’s suggestion about a digital scale: Excellent idea (and I have a digital scale). D’oh! But a) I haven’t been able to find any data on how much ND-11 POE should be added to a 2nd Gen Prius recharge (de nada in the shop manual), or a chart with recommended lubricant: refrigerant ratios; b) How would I calculate how much oil to add in an existing system – assuming not much is removed by the vacuum process? Sooo… c) I opted for measure–add–measure. But the Achilles heel in this method is those little oil measuring capsules… very hard to read.
    Q1: If there’s a better, affordable way to measure/evaluate the lubricant in an A/C system, I’d like to hear about it.
    2. Dr. Lech: Thanks for the video links… a few I hadn’t seen yet – always helpful & informative. a) I always download the MSDS, so I’m aware of R12a’s volatility but I don’t have a choice – R134a banned here since 1996. b) No garage, so I work outside with a big fan (to discourage mosquitos, black flies & deer flies). Fan also disperses VOCs. I always work w/ goggles & gloves (and CO2 fire extinguisher nearby ;-) c) Special vacuum hose will probably improve draw on vacuum pump… rather than go thru the yellow hose, then H&L manifold gauge hose(s). I’ll look into that (for DIY home mini-split heat pump being delivered next week). d) Great tips too about keeping refrigerant can in a bucket of water (why didn’t I think of that? ;-) and doing refrigerant leak tests when system is hot.
    3. I agree w/ Dr. Lech that the instructions that came with the ‘enviro’ R12a refrigerant he tested are questionable. Releasing the vacuum before charging defeats the purpose... sucks back-in all the nitrogen, oxygen & moisture just removed.
    Q2: Is there an equivalence chart for converting/adjusting R134a-to-R12a volume & ambient temperature compensation?
    BTW: If I’m not mistaken, the (freakin’ complicated) Prius A/C system’s computer constantly monitors pressure: if it drops below a certain value, it shuts-off voltage to the electric compressor to avoid burning it out due to low/no refrigerant & coolant.
    Thanks again to everyone for sharing their expertise, advice & opinions… this is a great forum for all Prius owners!
     
  17. ChapmanF

    ChapmanF Senior Member

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    Hold the phone ... what do you mean by "here"?

    Granted I don't live in Québec and I'm pretty much a stranger to the regulations there, but two things about that sentence take me greatly by surprise: (1) that 134a is banned, and especially (2) "1996" as the date of such a ban.

    The nearest thing I've been able to find is Q-2, r. 29, Regulation respecting halocarbons, Division III, air conditioning units in certain vehicles.

    That only prohibits CFCs, like the old R12. The in-force date of that section was 2012-09-01. R134a falls in the HFC category, so it is "a halocarbon other than a CFC", so it isn't banned by this section, and it even would be allowed as a retrofit in a unit that originally used a CFC.

    As far as Canada-wide regulations, I can find SOR 2016-137, Ozone-depleting Substances and Halocarbon Alternatives Regulations, Part 4, HFCs. Looks like HFCs, including 134a, can't be manufactured as new refrigerants, or imported or exported for most purposes. They can be reclaimed/recovered/recycled, and they can be imported if reclaimed/recovered/recycled. They can only be sold in refillable containers (no 12 ounce retail cans). Cars using 134a can't be manufactured for the 2021 model year or later, or imported if they are 2021 model year or later (except as the importer's personal vehicle). Businesses (including A/C shops, presumably) that have been granted consumption allowances have to reduce the amount allowed to 90% through 2023, then to 60% through 2028, then to 30% through 2033, then to 20% through 2035, to finally 15% as of 2036.

    None of that sounds like 134a has been banned since 1996.

    Is that in some other regulation that I didn't find?
     
  18. lech auto air conditionin

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    And by the way the low pressure switch in the Prius does not cut off the electric to the compressor until it’s already into an after the overheating zone of the compressor.

    and they often burn themselves out before that switch ever D energize the electric current to the compressor allowing it to self-destruct.

    It was a very poor safety design leave out a few sensors save a few dollars on production.

    I have several videos showing the Prius operating on nothing but vapor gas with no liquid in the system just a few psi of refrigerant.
    All you need is 44 psi of refrigerant to trip the sensor into staying on.

    slowly roasting the compressor to death
     
  19. Robert John

    Robert John Junior Member

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