Way to make the A/C compressor run?

Posted by Kyle97-clipse, Apr 5, 2010
420A Bolt-on Tech - Intake, exhaust, ignition, fuel system, cooling, etc - specific to 2G N/T DSMs. New Members must limit their 420A tech posts to this forum.

  1. Kyle97-clipse

    Kyle97-clipse Proven Member

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    Mahanoy City, Pennsylvania
    Okay so my A/C compressor is not kicking on. The green light is lighting but the compressor will not run. I know that if the system is low on freon it will not run. I am going to try and charge it, but to do that the compressor need to be running. Should i just send 12 volts down there? Please help thanks
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  2. 95blackGsTurbo

    95blackGsTurbo DSM Wiseman

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    Not recommended but remove the plug off of the cycling switch and jumper it with a wire in the plug and it will force the compressor on.
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  3. white92talontsi

    white92talontsi Proven Member

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    if its just low on freon then you can add freon and the compressor will start running.
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  4. Kyle97-clipse

    Kyle97-clipse Proven Member

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    No, because if the compressor is not running it will not allow the freon to enter the system
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  5. 95blackGsTurbo

    95blackGsTurbo DSM Wiseman

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    That is because you are charging the system incorrectly. You need to pull a vacuum on the system to remove the air/moisture, then the vacuum will pull in the R134a so the compressor can kick on. Even if you get some in there, the system won't function very well with air in the system and not knowing the exact amount going in either.
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  6. josh38127

    josh38127 Proven Member

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    Dont try to jump it just yet. Go grab a couple cans. Charge the system.When You get close to the right amount your commpressor will come on.

    To answer your question. No your commpressor doesn't have to be running to charge the system


    Adam is right you need a vac if you replaced something in the A/C system. But it sounds like you may just be low
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  7. Kyle97-clipse

    Kyle97-clipse Proven Member

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    Mahanoy City, Pennsylvania
    Okay so 95blackgsturbo what would you do in this situation? How do I pull a vacuum on the system?
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  8. white92talontsi

    white92talontsi Proven Member

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    You do not have to pull a vacuum on the system to charge it up. Just get some freon, start the car with the a/c on and start adding freon. If it is just a little low then when the pressure switch "sees" the freon it will start to cycle the compressor.
    Make sure to put the freon in on the low side.

    It is recommended to pull a vacuum though. Pull a vacuum and let it run for 30 minutes. close off the system and if it holds the vacuum then there are no leaks.

    I use Compressed Nitrogen at the shop to pressurize the system and then spray everything down with soapy water.

    You only need to pull a vacuum if you have to replace something in the system.
    I would disconnect the pressure switch and jump across the terminals to see if the compressor will run. If the compressor runs then try adding freon. If adding freon does not let the compressor run then the pressure switch is probably bad.

    If the compressor fails to run by jumping the terminals then you need to start checking things like the clutch air gap and what not. At that point it may be best for you to take it to someone qualified to work on A/C stuff.
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  9. 95blackGsTurbo

    95blackGsTurbo DSM Wiseman

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    Have it done professionally, or rent a vacuum pump and set of gauge's from your local parts store.
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  10. Kyle97-clipse

    Kyle97-clipse Proven Member

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    Okay so the problem is resolved I added freon and it kicked on it took a whole can but its full now. Just hope theres not a leak though
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  11. white92talontsi

    white92talontsi Proven Member

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    If it does go low again what you can do is add some UV dye to the system along with a can of freon. Then you can use a blacklight to find out where the system may be leaking.
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  12. 95blackGsTurbo

    95blackGsTurbo DSM Wiseman

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    If you needed to add, it was low. It doesn't evaporate.
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  13. bih55

    bih55 Proven Member

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    not to hijack the thread but what is the yellow and the the green light on the ac button
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  14. born2tune

    born2tune Proven Member

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    yellow, is the condenser on, working but not using freon,

    green is with the freon circulating (cools the cabin faster) yellow is just more like a cool fan.
    #14
  15. davidaham

    davidaham Proven Member

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    WOW I NEVER NEW THIS :ohdamn: THANKS FOR THE INFO.
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  16. jgm95gsx

    jgm95gsx Probationary Member

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    I am having similar symptoms with my 95 gsx.

    The a/c compressor is not kicking on. Whether the green or yellow a/c light is on, the signal doesn't appear to be making it to the relay. I can apply voltage to the relay and the a/c clutch will engage and the compressor will work and the very nice cold air will flow. I just charged the system, so it isn't low refrigerant that is keeping the compressor off.

    Does anyone have any other suggestions of things to check to figure out this issue? It is looking more and more like an electrical problem. :banghead:
    #16
  17. VelocitàPaola

    VelocitàPaola DSM N/T Moderator

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    You could also have too much refrigerant in the system. The dual pressure switch also switches off above a certain pressure (~370-455psi).

    Alternatively, the dual pressure or refrigerant temperature switches may be faulty.

    In any case, you should really start a new thread for your problem outside of the 420A Bolt-on Tech forum.
    #17
  18. 96mitsugsx

    96mitsugsx Proven Member

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    The yellow light is for econo mode, which means that the compressor automatically turns off at a higher cabin temperature. When you push the button twice it will turn green which means that the a/c system is in full blast. Which means that the compressor will automatically turn off less often than if you are in econo mode. The a/c system will have freon circulating whether you are in yellow or green mode. There is also no such thing as "just the condenser working".
    #18
  19. 4g63rice

    4g63rice Probationary Member

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    i know this post is kinda old but when i put the switch to change where the air blows too, to the windshield, is the yellow light on the AC switch supposed to be on even though i did not press it at all and i have the temperature on hot??
    #19
  20. VelocitàPaola

    VelocitàPaola DSM N/T Moderator

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    Start a new thread in the Newbie Forum for your question. Questions about 4G63 cars don't belong in this forum.
    #20

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