Anyway to test AC compressor myself?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by maximusdec, Jun 25, 2020.

  1. maximusdec

    maximusdec Member

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    My AC stopped working a few months back. It blows hot air. I don't drive it that much these days, maybe 3 days out of the month. From looking around AC repair is big money item. Plus can't find any independent shop to work on it in either the Houston area or Dallas area. So I thought maybe I can tackle it myself. The AC compressor doesn't kick on. Not sure if it low coolant or compressor is kaput. Bought one of those $20 refrigerant refill cans from Walmart. Since the compressor doesn't kick on the refrigerant doesn't flow in. Possible to test the compressor? What fuses should I check also? Thanks

    Edit: car is 2007 Prius with 251000 miles and this is the first major repair issue I have encountered in the 130K miles I have owned it
     
  2. lech auto air conditionin

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    well since you’re thinking about getting one of those little cans with the gauge on it. You could just stick the gauge on and let’s see if it reads over 45 psi your compressor should least try to engage you may hear a clicking sound. If there’s less than roughly 45 psi the pressure switch will not let any activation of the compressor to occur.

    If there is no pressure in the system I guess you could squirt a little inside to get the pressure up and then retry. If the compressor comes on you know it was because of the low refrigerant. But then then go and have it professionally refilled but you have to look for the leak. The most common leak point is on the condenser. If you go into my photo album I have some photos of Prius condensers and you could see the oil stains what they look like.
     
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  3. maximusdec

    maximusdec Member

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    Unfortunately it doesn't tell me what the pressure is. Just a green, yellow and red zone. It's on the red zone, which is supposed to be overcharged zone
     
    #3 maximusdec, Jun 26, 2020
    Last edited: Jun 26, 2020
  4. lech auto air conditionin

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    If it’s in the red zone and the compressor is not running most likely without being there or seeing it I am going to assume ( nice person/u/me) like my seventh grade teacher instructed us do not assume because you will make a (nice person, out of /YOU/ and /ME) but here it goes anyway. Thinking with a wild guess that red pressure probably starts about 45 psi or more. If this is true you apparently have enough pressure in the system for the safety switch is to have contact and when you press the button in the dash will tell the software in the computer that it is OK to start the compressor because there’s enough refrigerant in the system. But this is just a completely wild guess. You could take a strong flashlight and look at the condenser for some dirt and dust buildup that will be a dark shadow built up on oil residue. This would give a good indicator of a leak. I only choose a condenser because it is the number one culprit when it comes to leaks and they do it yourself person can easily access it and see it rare for the hoses or lines to leak but it is possible. If the evaporator is leaking there’s no way for a do it yourself person to check that. In my area you could go to an auto parts store like O’Reillys and they do free code checking the hook their little handheld scanner up and pull codes for you. If you get a code and when they translated it says over amp. That is usually the compressor. When you see the code saying sun sensor totally ignore that. After this you will be taking it to a professional. Unless you to do it yourself type of person who can change their own car raider change their own starter change their own alternator. Then you might be up for the task of changing your own compressor and condenser.
     
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  5. m.wynn

    m.wynn Senior Member

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    You could try drawing a vacuum on the system using a set of manifold gauges and a vacuum pump and see if that will create enough refrigerant draw to get your compressor to kick on... Drawing a vac and observing it for an hour will also confirm whether or not you have a leak.

    If turning your ac on yields this rhythmic, loud "rattle" as @lech auto air conditionin refers to it in his video:



    ...there's a good chance your compressor looks like this under the cover:

    DSCN2347.JPG DSCN2348.JPG

    My younger daughter's '07 was making the the "rhythmic rattle" 5 times at ac start-up, followed by radio silence from the compressor. Popping the cover off yielded the pics:rolleyes:...

    I eBay-ed a salvage compressor from an "09 with 180k miles for $70 shipped and swapped it in without adding ND-11 and without changing the condenser. This northeastern (super salt crusted) car will never see radiator/condenser work unless there is a leak in one of them. How much money you want to spend on your 1/4 million mile '07 will determine longevity of the fix, so the $80 I spent ($10 for 2 cans of Supertech R134a) likely isn't a multi-summer fix, we'll be happy to get it through this one. Three weeks in, and it's blowing as cold as it ever did previously, ~40-44 degrees F measured at the upper vents.
     
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  6. edthefox5

    edthefox5 Senior Member

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    Best way to kill a 2007 Prius is to not use it and let it sit for days. It will kill the hybrid battery too for sure.
     
  7. maximusdec

    maximusdec Member

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    No oil spots on the condenser. The compressor kicked on yesterday when I was tinkering with the car but it didn't sound good. So am guessing it's the compressor. Bought a used compressor and will try swapping it out next time I have time.

    Good info. Ya I bought a used compressor from salvage yard. Will try swapping it out.

    True. Unfortunately my job keeps me away for weeks at a time
     
  8. lech auto air conditionin

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    Measure the oil that comes out of the old compressor to do a oil balance if you don’t know what oil balances look it up.

    Then after pouring out the oil from the old compressor put some brake cleaner carburetor cleaner inside the old compressor both ports jiggle it around shake it around and then pour it out into a clean glass or white bowl and if you see metal particles coming out you need to replace the condenser

    And if you don’t have to replace the condenser at least replace the desiccant bag that’s located in the condenser in that large pipe attached to the side if it looks like a big tube
     
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  9. maximusdec

    maximusdec Member

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    Are you talking about the dryer?
     
  10. lech auto air conditionin

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    Yes
     
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  11. maximusdec

    maximusdec Member

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    Did you have metal shavings in the oil that came out of the old compressor?
    So took the old compressor off and oil was silverish black from metal shavings. There was so much shavings in it, it turned it greyish black. Does this mean the metal shavings have traveled with the oil through out the system? Was talking to a mechanic and he said the system will need a flush. Why did you recommend a condenser change if there was metal shavings?
     
  12. lech auto air conditionin

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    If it’s that dirty you even need to pull the expansion valve out and flush the evaporator that’s a complete system cleaning .
     
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  13. maximusdec

    maximusdec Member

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    This job is going from simple to a nightmare. I might just have to put up with no AC until next summer.
     
  14. maximusdec

    maximusdec Member

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    What color is the OEM compressor oil?The used compressor I bought has a yellowish liquid.

    How much oil and refrigerant does the new dry system take on the Prius?
     
  15. lech auto air conditionin

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    The oil is supposed to be crystal clear yellowish sounds either it’s very oxidized and contaminated or there might be a small quantity of UV dye in it if you have one of those cheap little UV lights that you can get from an auto parts store you can test that theory out.

    The quantity of refrigerant is on the sticker underneath the hood of your car it’s different on different cars
     
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  16. lech auto air conditionin

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    you can not draw a vacuum to draw refrigerant to start a compressor. there is a pressure sensor to stop the compressor to protect it from starting if there is not refrigerant.

    This is DANGEROUS and messy especially if there is green UV dye in the system. As soon as you connect a host to the vacuum pump with refrigerant in it the pressure of the liquid refrigerant will blow right through the vacuum pump instantly BLASTING OUT all the vacuum pump oil with great force. Depending on the pumps exhaust port sideways or up into you face.
    (ASK ME HOW I KNOW) I have been hooking up vacuum pumps since I was 12, do you think I have never made a mistake being in a rush ???... Vacuum pump oil dose not taste bad it just coats your mouth with mineral oil but the taste of PAG double end cap DENSO oil OMG nasty bitter I can not describe the taste it is so bad. Brush you teeth, mouth wash, mint candy, Coke Cola, gum, nothing gets the taste out of your mouth.

    If you get pure 100% PAG doubble end capped DENSO oil in you mouth a whitest film layer of thin skin fall (peals off) I cant imagine if it gets in you eyes. I was wearing safety glasses.
    I have gotten vary small amount in eyes it burns. When it get in the air as a vapor it irritates the throat and lungs.


    Drawing a vacuum if a vary poor way to look for a leak, many time dose not work at all even on vary big leaks. The pressure difference is only 14.7 PSI vary little. If the leak is at a rubber hose or oring coated with a film of oil it often pulls inwards sealing it self.
    Using refrigerant under static conditions ( engine or compressor not running) the PSI will only get as high as the ambient temperature. example 70F = 70 PSI then use a electronic leak detector. When using dry nitrogen you can raise the PSI to 150 to 170 PSI that is were you will start finding most leaks and you can use a bubble soap leak method.[/QUOTE]
     
    #16 lech auto air conditionin, Jul 24, 2020
    Last edited: Jul 24, 2020
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