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Thread: System Charge

  1. #1

    System Charge

    Carrier 2.5 Ton Unit Replaced 2001 Compressor to new 2012. Freon 22.
    Please I need help on system re-charge, this is my first compressor replacement job. I did recovered 4lb, 8oz, before removing compressor, after completing replacement of compressor & vaccumed. I charge the froen from recover cylinder. But there is still gas left in cylinder which cannot recharge due to pressure equal. Before I charge new freon22 I want make sure I am not over charging. Since guages are showing me Lowside 70PSI Highside 225PSI pressures look like to me high atleast lowside but temps are not right in evaprator. Should I go ahead charge more freon which will bring down Lowside PSI & Temp. I am sure I did not put all freon I removed system plate says 4lb 3oz but I have charged about 3lb.
    Last edited by adroit; 06-30-2012 at 01:54 AM. Reason: correction

  2. #2
    Join Date
    Jun 2012
    Location
    Minnesota
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    You charge systems by superheat or subcool depending upon a TXV or Fixed Orifice, not on weight. Weight is a starting point not an exact measure. As to weather or not to add more refrigerant I'd say call in a professional, and not risk damaging the new compressor. I only say that because u said..

    there is still gas left in cylinder which cannot recharge due to pressure equal.


    Personally I would never put used refrigerant back into a system i just replaced a compressor on but thats just me.

    Oh an Welcome to the Forum, Im new too!

  3. #3
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    entertain me with the reason the compressor was changed
    It`s better to be silent and thought the fool; than speak and remove all doubt.

  4. #4
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    Quote Originally Posted by dandyme View Post
    entertain me with the reason the compressor was changed
    ...and entertain ME with why you are not asking your service manager, or the guy standing next to you who is making sure you are ready to go from helper to journeyman.......
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

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  5. #5
    Join Date
    May 2009
    Location
    oklahoma
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    184
    Yeah what others have said, but calm down check the paperwork with the unit for charging procedures and line set weights. Sometimes you have to start the systems to get the rest of the charge to take, or warm the Freon bottle. Though that shouldn't be the case this time of year. If you weighed in less freon then the nameplate charge your not overcharged.

  6. #6
    Join Date
    May 2009
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    oklahoma
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    Oh and don't be afraid to ask for help here or at work everyone has brain farts now and then.

  7. #7
    Join Date
    May 2009
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    oklahoma
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    Also do you know why the compressor went out?? Hope it wasn't a burn out. I too personally would not reuse refrigerant from a failed compressor. Good chance of contamination.

  8. #8
    Reason for change of Compressor is starting wedding short, meter was reading open between run to common, run to ground, common to ground, start to run & common, but short on start to ground. I just finish HVac from school and working on my home unit. Thats why I used remove freon because compressor was not burned out. Name plate said 4lb 3oz, according to Nplate its low on freon but readings are high 70PSI & 225PI, I am just curious new compressor might take less freon because they have updated part number and they are not making anymore old compressor. Bristol compressor old model# H29B28UABCA and new model # H22J29BABCA.

  9. #9
    Join Date
    Apr 2012
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    Negative.

    If you're fresh out of school then Im sure you remeber subcooling and superheat.

    If its fixed orifice use super heat. There might be a chart on the inside of the control panel that you can get total SH from outdoor ambient.

    If its a TXV use subcool.

    Its thats simple.

  10. #10
    Join Date
    Apr 2012
    Location
    Cleveland
    Posts
    606
    11 yr old carrier is probably a fixed metering device, but check the indoor coil to be sure. I hope you replaced your start components and replaced or added a drier. Make sure you check your amp draws and voltages too.

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