Air conditioner blowing warm air

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Shawn W., Jun 8, 2022.

  1. Shawn W.

    Shawn W. New Member

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    Since you're an auto air conditioning specialist, what would you recommend?
     
  2. Tombukt2

    Tombukt2 Senior Member

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    I've seen some of this up and down gauge business on old Toyotas with the radial compressors even with the Tecumseh style spraying water on the condenser and all that sort of stuff you can see the pressures go up and down by the cooling effect on the gas and all that great stuff I just like to have it full close to the proper amount the 1.4 lb or 1.32 or whatever it is under there so if I can get close to that into the system when it's empty or vacuumed or doesn't have any gas in it then I'm okay I'm making cold air and I'm happy nothing's broke all the rest of it should be okay the fans and all that worked before so I will assume they're going to be fine now and actually we're having no air conditioning problems when I change my engine and plugged my electric air conditioning back in which it was never removed from the car all the gas was still in the system and nothing was touched the compressor was unbolted and set to the side when I plugged it back up I kept getting some kind of communication air like the car wasn't talking to the compressor or vice versa I didn't have time to play with it so I just left it disconnected for about 3 weeks before it started to get hot and then about a week and a half ago I just said screw it I plugged it up while the car was at rest first thing in the morning for the car been run or anything I went back in and had my breakfast came back out and started the car pushed the button for the air condition auto button and it was working so I have left the left alone cleared the codes that were there and waiting for it to code again or not it's ice cold like it always has been
     
  3. lech auto air conditionin

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    Unfortunately mechanics look at bubbles in a psych class and say it’s OK if they don’t see any.

    Unfortunately mechanic say the refrigerant pressure (“and I mean they go by pressures”) are okay if they don’t see the high side in the upper 300s or 400 and the low side down below 10 psi or into the negative psi.

    which none of that tells them whether the system is correctly filled two or 3 ounces too low or two or 3 ounces too high makes a real big difference on a small tiny system like a Prius that has a incredibly small thin evaporator that relies on a critical charge of being exact to give out it’s for BTU rating.

    so the first thing a technician does of course is hook up the refrigerator identifier to tell if the last person who charged it had contaminated refrigerant which the majority of shops do because they don’t owner refrigerant analyzer when they recover and recycle refrigerant from other peoples cars.

    Then you completely recover all the refrigerant out of the vehicle

    throw it on the vacuum pump until it reaches around 500 µm or below. Now at least you’re sure you got all the air out and at least started to remove some moisture contamination.

    Now we charge it to exactly what the manufacture specified by way to only not by shaking little cans into the system.


    now we have a known good starting point to do diagnosis from that’s just the beginning minimum procedures a technician who has good practices will start from.

    (“ now if all of a sudden AC started blowing cold and working good there’s no more diagnosis to do because that was the only problem”).
    Only problem is finding somebody who will do it correctly that is the biggest problem I have when trying to recommend a customer to go somewhere else when I’m too busy or I can’t do the job.

    The pressure switch can be diagnosed by following the troubleshoot procedures they have downloaded.

    The Prius AC system in the world of HVAC on a rating of 1 to 10 in complexity it’s about a 3 something a fifth grader can diagnose as a grammar school science project.
     
  4. Tombukt2

    Tombukt2 Senior Member

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    And the quite pleasant surprise is that they all seem to work all any of the ones I've picked up needed was to be gassed up or vacuumed down and gassed up and they've all worked every one of these Priuses that I've sat in and bought and even friends cars that they bought with the air conditioner not running generally it's been vacuumed down make sure there's no leak which usually it won't vacuum if there is fix that gas it up and generally it's ice cold generally and I've done this about 10 or 12 cars all Gen 2's and I own a gen 3 we almost had to do this too
     
  5. jdenenberg

    jdenenberg EE Professor

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    My 2004 Prius AC stopped working in 2005. The Toyota tech blame it on a stone hitting the condenser coil, causing a leak. They wanted $$$$ to fix it (not covered by warranty) so I went to my local garage and he tried a "stop leak" solution and charged the system back up. The AC was still working in 2016 (288k miles) when I traded the 2004 in for a 2016.

    JeffD
     
  6. Saib

    Saib New Member

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    Hello there, I’m confused how to add a question here?? I’m a new member
     
  7. Tombukt2

    Tombukt2 Senior Member

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    I personally have never had good luck with the stop leak business. Usually I just bite the bullet and buy the new line or the new condenser or whatever is leaking once I replace that Toyota denso air conditioners have been infallible in my world they have been the least of the problem of any vehicle that we have ever owned since KE series Corollas of the '60s so I don't know. I went through all kinds of hoopla with general motors air conditioning in the '80s and Chevy citations and all that nonsense nothing but a black hole of repairs. On our Toyotas dating back to the late '60s early '70s with hang on units under the glove box and Tecumseh style compressors under the hood use lots of energy but they almost never broke 20 years later still works ice cold.
     
  8. Tombukt2

    Tombukt2 Senior Member

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  9. Tombukt2

    Tombukt2 Senior Member

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    Oh man go up to the top left of page Hit the drop down bar select Prius drop down select Prius 2 it drops down you want to probably go to the technical discussion from there you'll see a thing start a new thread when you put in to start a new thread like my hybrid battery is going bad it won't let you start a thread until you look at the list of threads already generated about this particular topic then you can scroll down further start typing and go from there. There's a lot of reading to do first most everybody has asked the same question at least a few hundred times and the round and round to get to the endpoint is generally very similar. So just read first and then you can try and get people to decipher their ciphers. Good luck man
     
    Saib likes this.
  10. Shawn W.

    Shawn W. New Member

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    It's been a while since I've commented here, but the problem isn't yet fixed. However, I took it to an auto A/C specialist shop and they said that there was no refrigerant. They flushed it and refilled it, but it still doesn't work. Unfortunately, they still have no idea what the problem is, except a suspicion that it MIGHT be the compressor, which they don't know for sure since they've never had a Prius in their shop, and they don't know how to properly test it. Any suggestions as to where I can go from here, and what the problem may actually be?
     
  11. tracy ing

    tracy ing Active Member

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    When mine went bad, I just ordered a rebuilt unit for 150 bucks and replaced it.
     
  12. TMR-JWAP

    TMR-JWAP Senior Member

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    You can look in the AC section of the repair manual. It has troubleshooting start on page AC-28

    Service Manuals - Google Drive

    Page AC-28 lists these as the most common causes for no cool air coming out (in order of most common) with the page to go to for further troubleshooting.

    1. Volume of refrigerant AC-136
    2. Refrigerant pressure AC-136
    3. Pressure switch circuit AC-59
    4. Air mix damper control servo motor circuit AC-77
    5. Air mix damper position sensor circuit AC-63
    6. Room temperature sensor circuit AC-42
    7. Room humidity sensor circuit AC-89
    8. Ambient temperature sensor circuit AC-46
    9. A/C inverter circuit AC-93
    10. Air conditioning amplifier AC-28
    11. Multiplex communication circuit MP-1
     
    #52 TMR-JWAP, Aug 5, 2022
    Last edited: Aug 5, 2022
  13. Boblay

    Boblay New Member

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    Thanks for this tips
     
  14. Tombukt2

    Tombukt2 Senior Member

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    So when you're non-working system is turned on the car is ready the system is on the blower is blowing everything is supposed to be happening the temperature is set to low. If you get out of the car and touch the fat silver hose that runs past the front of your engine is it cold very cold and the little tiny line is very hot is this a fact? Do you hear the compressor whining it sounds like an electric motor spinning quite quickly yes or no?
     
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