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Prius A/C Question

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by 2genprius07, Jul 13, 2018.

  1. 2genprius07

    2genprius07 Junior Member

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    Hello all, I have been reading here for years and really appreciate the insight everyone has provided.

    So I have an '07 Prius that has been running great since the day I got it. I get the oil changed every 5k miles at the dealership and do all other maintenance by myself with help from Amazon and the guides here.

    The main issues I've had with the car has been the A/C, which I believe is due to living in Tampa and keeping the A/C on max cool set to temp Low at highest fan speed pretty much every time I drive my car.

    3 years ago I had an issue where the fan wouldn't turn on unless I banged the plastic underneath it or used a stick to jumpstart it. I read on here that it was the blower fan most likely so I ordered one on Amazon for $45 or so and replaced it and sure enough it worked great. Fast forward 3 years and the same thing happened with the new one. I went through the same process recently buying a new one on Amazon and replacing it and the fan is working great again.

    My only issue with the car right now is that the A/C is cool, but never really gets that cold. I believe this is the reason I need to run the fan on the highest setting while driving it since it doesn't get all that cold and takes a while to get there.

    My budget is pretty tight so I would like some advice. I've read that I can either take it to the dealership and have them add refrigerant to the system and fix the non-freezing air issue, but this can cost $100's, which if I can avoid I would happily do any work myself.

    The other option that worries me a little bit thinking about is buying a can of the special for hybrid refrigerant without oil and buying a gauge, and trying to do this myself. I haven't found a good guide and haven't found definitive opinions about how safe this is.

    Like I said, currently the A/C is liveable with cool air on the highest fan speed, however I would greatly like to have the air colder as I live in South Florida and it's extremely hot!

    Thanks for reading and any insight you may offer!
     
    #1 2genprius07, Jul 13, 2018
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Buy a can of pure R-134a (which means no compressor oil added), and a hose that has a low side pressure gauge on it. Find the low pressure port, which has a grey cap with a big "L" on it. Attach the can to the hose. Attach the hose to the fitting that was exposed when you removed the "L" cap. Note the pressure in the system before you start the Prius.

    The refrigerant does not have to be designated for hybrid vehicles. It just has to be pure R-134a.

    Then make the Prius READY. Turn on the AC to MAX COLD, highest fan speed. See what the system pressure is with the compressor running, which will be less than the prior reading when the car was off.

    Add refrigerant up to the point where the low pressure measures 30 psi. This is much lower than most automotive AC systems require, so ignore any markings on the gauge or the instructions that come with the hose. (I am assuming that your ambient air temp is around 90 degrees F, which should not be too far off right now in the Florida summer weather. The higher the ambient air temp, the higher the system pressures will be.)

    After you have the low pressure side up to 30 psi, see how the air conditioning performance is. If it is not satisfactory, look at the sight glass on the high pressure side. If you see bubbling in the sight glass, add a bit more refrigerant but do not exceed 36 psi. If the sight glass shows no bubbling, then do not add more refrigerant.

    The difference in air conditioning performance will swing widely with small additions to the refrigerant, so add the refrigerant slowly and carefully. Good luck.
     
    #2 Patrick Wong, Jul 14, 2018
    Last edited: Jul 14, 2018
    Tideland Prius, 2genprius07, fotomoto and 2 others like this.
  3. 2genprius07

    2genprius07 Junior Member

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    Thank you very much for spelling out what I need to do, this is exactly the reply I was looking for!!! I will update with how everything goes! I'm just nervous trying to find pure R-134a without an hidden added oil. I looked in Walmart and on Amazon the other day and there is plenty of R-134a out there but IDK how to tell if it has no oil, will it explicitly state that?
     
    #3 2genprius07, Jul 14, 2018
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    #4 Patrick Wong, Jul 14, 2018
    Last edited: Jul 14, 2018
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  5. 2genprius07

    2genprius07 Junior Member

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    Thank you very much, I will go to the store tomorrow and buy what you recommended and attempt what you recommended.
     
    #5 2genprius07, Jul 14, 2018
  6. #1 Toyota salesman

    #1 Toyota salesman Member

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    $100 deposit, and AutoZone will "Loan" you a set of manifold gauges
    I tend to dissuade people from working on their own AC, if they're unfamiliar, but having lived in FL...
    One of the reasons I bought my Prius, is I got a crazy deal on it, because the compressor was garbage. Fortunately I've been working on automotive AC, for 15 years as a hobby.

    Posted via the PriusChat mobile app.
     
    #6 #1 Toyota salesman, Jul 14, 2018
  7. JC91006

    JC91006 Senior Member

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    You can't use those gauges in a prius because it gets contaminated from the previous user
     
    #7 JC91006, Jul 14, 2018
  8. #1 Toyota salesman

    #1 Toyota salesman Member

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    You'll be lucky if there is .1 oz of oil total in all three lines and the manifold itself

    Posted via the PriusChat mobile app.
     
    #8 #1 Toyota salesman, Jul 14, 2018
  9. #1 Toyota salesman

    #1 Toyota salesman Member

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    Personally, I have two sets of manifold gauges (hybrid/non) and my own 2 stage vacuum pump. A deep 2 stage will clear the lines

    Posted via the PriusChat mobile app.
     
    #9 #1 Toyota salesman, Jul 14, 2018
  10. ChapmanF

    ChapmanF Senior Member

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    I keep thinking the best good-instrument investment to make first might be a good micron gauge (there seem to be fairly affordable ones now, though I don't know anything about that one in particular).

    Without a good gauge, it can be hard to know what vacuum was really achieved. With a cheap pump, you might never know if the vacuum ever got deep enough, and on the other hand, with a good two-stage pump but no gauge, you might not know if the vacuum went below 200 microns, deep enough to risk separating out the components of the compressor oil (as discussed on p. 33 of this).

    -Chap
     
    #10 ChapmanF, Jul 15, 2018
  11. 2genprius07

    2genprius07 Junior Member

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    This is what I purchased, will it work? I see no mention of any oil, just the r-134a refrigerant.

    Refrig.png
     
    #11 2genprius07, Jul 15, 2018
  12. Patrick Wong

    Patrick Wong DIY Enthusiast

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    That should be fine, I assume that the hose can be transferred to another can after the original can is depleted?

    I also noticed that this particular can is 16 ounces which is much more than you will need. The capacity of the system is 15.9 ounces assuming that you are starting from a vacuum.

    You probably need only a few ounces of refrigerant to be added.
     
    #12 Patrick Wong, Jul 15, 2018
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  13. 2genprius07

    2genprius07 Junior Member

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    Thank you for the advice. I will attempt this when I get a free moment after work, this week. Will update.

    EDIT: Also to answer your question, it looks like a simple screw on type nozzle so I'd assume it can be removed afterwards no problem.
     
    #13 2genprius07, Jul 15, 2018
  14. 2genprius07

    2genprius07 Junior Member

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    UPDATE: So I did exactly what Patrick Wong said (THANK YOU AGAIN!) to 36 psi on the low side with the A/C on max cold/max fan and it felt a little colder, added a tiny bit more so it's still around 36 psi and now after driving around the past few days the A/C is much much colder! Can't be more happy with this $20 refill vs. the amount they would charge at the dealership. THANK YOU!!!
     
    #14 2genprius07, Jul 20, 2018
    SFO and Patrick Wong like this.
  15. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. Can you estimate how many ounces of refrigerant were added?
    2. Don't be surprised when this turns out to be a temporary fix. Your AC system has a leak somewhere, the open questions are where is the leak, and how bad is the leak.
     
    #15 Patrick Wong, Jul 20, 2018
  16. 2genprius07

    2genprius07 Junior Member

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    At most 2-3 ounces out of the 16 oz. can. The pressure when the car was off was over 100 psi, however with the ac and fan on max it went down to an estimated 28-30 psi. I added slowly and it only was noticeably colder close to the 36 psi mark, but it got there fast and the can feels basically full. Like you said the gauge had 36 PSI in the middle of the "adequate" reading, but it was cool and I stopped because I didn't want to add too much pressure like you said. Right now it's at 36 PSI and very cold. Even if it lasts like this for a year, unless the "leak" gets bigger I can use this can for a few more times.
     
    #16 2genprius07, Jul 20, 2018
  17. olerox

    olerox Junior Member

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    Great thread of info re: A/C charge. thanks guys.
     
    #17 olerox, Jul 20, 2018
  18. padroo

    padroo Senior Member

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    You should have a thermometer in one of your A/C vents inside your car so you know the actual temperature.
    A really cold system would put out in the low 40's.
    They are pretty cheap.
     
    #18 padroo, Jul 20, 2018
  19. 2genprius07

    2genprius07 Junior Member

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    Just wanted to update everyone: It’s been about 7-8 months since I “recharged” my A/C and it is still very cold!! The method outlined above works well and is easy and cheap. Thanks again for the help/advice!!
     
    #19 2genprius07, Mar 2, 2019
  20. padroo

    padroo Senior Member

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    Glad it worked out for you.

    It will be some time before we use our AC up north.:)
     
    #20 padroo, Mar 2, 2019
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