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  1. #1
    Join Date
    May 2011
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    CA
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    123

    Johnson controls All Range

    I was given one of these http://cgproducts.johnsoncontrols.co...PDF/125454.PDF by a refrigeration mechanic that I know and was told in so many words to "learn it inside and out, take it apart, screw with it, break it, fix it, but learn how it works." I read the online manual, but am still a little confused. I'm going to ohm the contacts as I adjust the pressure settings, but i'm not sure the switch will close since there's no pressure on the capillary tube (it's just sitting on my bench, not installed on a system). He asked me what I thought it did, and I asked him what it was connected to and he said "liquid line of a small rooftop condensing unit". At first I thought it was a condenser fan cycling control...ie., head pressure control. In other words, when the pressure is above a certain point the condenser fan kicks on. But I also see there is a high pressure control that opens the circuit above a certain pressure...which would lead me to believe that it somehow switches (cuts out) the compressor above a certain head pressure. I realize it can't do both. Can anyone lead me in the right direction here? I know they're widely used in one on one systems and want to learn more about them...

  2. #2
    Join Date
    Feb 2008
    Location
    California
    Posts
    2,066
    You're going to technical school right?

    I'm just curious, what book is the course being taught from?

  3. #3
    Join Date
    Jun 2005
    Location
    Las Vegas NV
    Posts
    1,152
    The manual you have is for the Johnson Controls P70, P72, and P170 series controls, not just one control.

    Look at the back of the control, or inside the cover, and get the model number. Then go to page 9 of the manual.

  4. #4
    Join Date
    May 2011
    Location
    CA
    Posts
    123

    Red face

    Quote Originally Posted by powell View Post
    The manual you have is for the Johnson Controls P70, P72, and P170 series controls, not just one control.

    Look at the back of the control, or inside the cover, and get the model number. Then go to page 9 of the manual.
    It says P70AA-118...damn, i shoulda figured that before i posted.

  5. #5
    Join Date
    May 2011
    Location
    CA
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    Quote Originally Posted by Phase Loss View Post
    You're going to technical school right?

    I'm just curious, what book is the course being taught from?
    Refrigeration and Air conditioning Technology. I have the 2009 ed. (at least I think it's 2009 ed).

  6. #6
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,574
    Quote Originally Posted by Iceneck View Post
    I was given one of these http://cgproducts.johnsoncontrols.co...PDF/125454.PDF by a refrigeration mechanic that I know and was told in so many words to "learn it inside and out, take it apart, screw with it, break it, fix it, but learn how it works." I read the online manual, but am still a little confused. I'm going to ohm the contacts as I adjust the pressure settings, but i'm not sure the switch will close since there's no pressure on the capillary tube (it's just sitting on my bench, not installed on a system). He asked me what I thought it did, and I asked him what it was connected to and he said "liquid line of a small rooftop condensing unit". At first I thought it was a condenser fan cycling control...ie., head pressure control. In other words, when the pressure is above a certain point the condenser fan kicks on. But I also see there is a high pressure control that opens the circuit above a certain pressure...which would lead me to believe that it somehow switches (cuts out) the compressor above a certain head pressure. I realize it can't do both. Can anyone lead me in the right direction here? I know they're widely used in one on one systems and want to learn more about them...
    Do you have access to nitrogen and a set of manifold gauges?

    That's a GREAT way to set and test pressure controls.

  7. #7
    Join Date
    May 2011
    Location
    CA
    Posts
    123
    Quote Originally Posted by jpsmith1cm View Post
    Do you have access to nitrogen and a set of manifold gauges?

    That's a GREAT way to set and test pressure controls.
    I have both at work...I'm home now. But, I'd have to find the male fitting for the flare connection...not sure what size it is. That's a great idea, though! Once I find the fitting, I could solder it onto a pipe, then solder on a T with a schrader valve for my guages, then cap both ends and use the nitrogen regulator to adjust pressure and check for continuity between the two terminals at various pressures...

    I adjusted the high pressure side all the way down (to what I think is atmospheric pressure, the scale didn't go that far), heard a "click", and got continuity between the two terminals.

  8. #8
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,574
    Quote Originally Posted by Iceneck View Post
    I have both at work...I'm home now. But, I'd have to find the male fitting for the flare connection...not sure what size it is. That's a great idea, though! Once I find the fitting, I could solder it onto a pipe, then solder on a T with a schrader valve for my guages, then cap both ends and use the nitrogen regulator to adjust pressure and check for continuity between the two terminals at various pressures...

    I adjusted the high pressure side all the way down (to what I think is atmospheric pressure, the scale didn't go that far), heard a "click", and got continuity between the two terminals.
    You could just wrench it onto the manifold.

    a 1/4" male x 1/4" male fitting is pretty common.

  9. #9
    Join Date
    May 2011
    Location
    CA
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    Quote Originally Posted by jpsmith1cm View Post
    You could just wrench it onto the manifold.

    a 1/4" male x 1/4" male fitting is pretty common.
    Just did so and it fits....

  10. #10
    Join Date
    Dec 2010
    Location
    Woodbridge Twp, NJ
    Posts
    1,307
    If you screw it onto the low side of the manifold, you can pressurize and see where the contacts open and close.
    Every customer you take for granted today will be someone else's tomorrow.

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