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Thread: Schrader valve not flowing gas

  1. #1
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    Schrader valve not flowing gas

    Currently working on a Turboair MST-60-24 which has got a low refrigerant charge. High side running at about 210 (design pressure 312). Store manager told me they have it refilled every year or so, so low charge seems to verifiably be the case.

    Problem is, I go to hook up my service gauge to the low side and get nothing. Tried putting gas through, seems like I only built pressure in the line (shot up quickly and stayed there, no high side pressure increase). There is pressure in the low side for sure, since I stuck my knife on the stem and got some gas to shoot out.

    Not sure what I'm doing wrong here. Figured I'd ask here before I went out and bought new lines or had to do any recovery/purging. My gauges work fine on any other system, and the service port on this Turboair doesn't show any suspicious signs. Thanks for any help.

    edit: adding that the compressor was indeed running while I was hooked up

  2. #2
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    Using the right end of the hose?

  3. #3
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    Either no depressor in the hose, or not set far enough out.


    Sent from my iPhone using Tapatalk

  4. #4
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    Quote Originally Posted by heatingman View Post
    Either no depressor in the hose, or not set far enough out.


    Sent from my iPhone using Tapatalk
    I've also seen the depressor in the hose end deformed and or the Shrader presser bent so it does not depress and open the Shrader valve

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  6. #5
    Join Date
    Feb 2018
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    Just cheat it and use your VCRT's. Then put in new Schraders and see what happens. Willing to put money on your depressor isn't out far enough though.

    Sent from my SM-N960U using Tapatalk

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  8. #6
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    Design pressure 312?
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Why is it that those who complain the most contribute the least?
    MONEY CAN'T BUY HAPPINESS. POVERTY CAN'T BUY ANYTHING

  9. #7
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    Quote Originally Posted by 2sac View Post
    Design pressure 312?
    Facilities Manager!

    I still say he has the straight end on !

  10. #8
    Join Date
    Jan 2020
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    So this is a make table? Likely 134a. If I'm seeing 210 high side pressure on a cap tube 134a system and it's not 130degrees ambient I'm looking at the whole rest of the system.
    The no low side pressure makes me think maybe you have a plugged cap tube......
    Especially with head pressure that high. I'll bet you are making lots of wax in the system
    You don't squat with your spurs on.
    And you NEVER put the torches away before pressure testing.

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  12. #9
    Join Date
    Jan 2010
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    Design Pressure = Test Pressure
    Could be R404a
    The new tables are R290
    Of course he could be reading design for high side.
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